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Find video protocols related to scientific articles indexed in Pubmed.
G-Protein Estrogen Receptor as a Regulator of Low-Density Lipoprotein Cholesterol Metabolism: Cellular and Population Genetic Studies.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 11-15-2014
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Estrogen deficiency is linked with increased low-density lipoprotein (LDL) cholesterol. The hormone receptor mediating this effect is unknown. G-protein estrogen receptor (GPER) is a recently recognized G-protein-coupled receptor that is activated by estrogens. We recently identified a common hypofunctional missense variant of GPER, namely P16L. However, the role of GPER in LDL metabolism is unknown. Therefore, we examined the association of the P16L genotype with plasma LDL cholesterol level. Furthermore, we studied the role of GPER in regulating expression of the LDL receptor and proprotein convertase subtilisin kexin type 9.
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Loss-of-Function Mutations in ABCA1 and Enhanced ?-Cell Secretory Capacity in Young-Adults.
Diabetes
PUBLISHED: 08-14-2014
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Loss-of-function mutations affecting the cholesterol transporter ABCA1 impair cellular cholesterol efflux and are associated with reduced HDL-C levels. ABCA1 may also be important in regulating ?-cell cholesterol homeostasis and insulin secretion. We sought to determine whether loss-of-function ABCA1 mutations affect ?-cell secretory capacity in humans by performing glucose-potentiated arginine tests in 3 subjects homozygous for ABCA1 mutations (age 25±11 years), 8 heterozygous subjects (28±7 years), and 8 normal controls pair-matched to the heterozygous carriers. To account for any effect of low HDL-C on insulin secretion, we studied 9 subjects with isolated low HDL-C with no ABCA1 mutations (26±6 years), and 9 pair-matched controls. ABCA1 mutation homozygotes exhibited enhanced oral glucose tolerance and dramatically increased ?-cell secretory capacity that was also greater in ABCA1 heterozygous subjects than in controls, with no differences in insulin sensitivity. Isolated low HDL-C subjects also demonstrated an increase in ?-cell secretory capacity, but in contrast to those with ABCA1 mutations, exhibited impaired insulin sensitivity, supporting ?-cell compensation for increased insulin demand. These data indicate that in young-adults loss-of-function mutations in ABCA1 may be associated with enhanced ?-cell secretory capacity and normal insulin sensitivity, and support the importance of cellular cholesterol homeostasis in regulating ?-cell insulin secretion.
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Homozygous familial hypercholesterolaemia: new insights and guidance for clinicians to improve detection and clinical management. A position paper from the Consensus Panel on Familial Hypercholesterolaemia of the European Atherosclerosis Society.
Eur. Heart J.
PUBLISHED: 07-22-2014
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Homozygous familial hypercholesterolaemia (HoFH) is a rare life-threatening condition characterized by markedly elevated circulating levels of low-density lipoprotein cholesterol (LDL-C) and accelerated, premature atherosclerotic cardiovascular disease (ACVD). Given recent insights into the heterogeneity of genetic defects and clinical phenotype of HoFH, and the availability of new therapeutic options, this Consensus Panel on Familial Hypercholesterolaemia of the European Atherosclerosis Society (EAS) critically reviewed available data with the aim of providing clinical guidance for the recognition and management of HoFH.
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Whole exome sequencing of familial hypercholesterolaemia patients negative for LDLR/APOB/PCSK9 mutations.
J. Med. Genet.
PUBLISHED: 07-01-2014
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Familial hypercholesterolaemia (FH) is an autosomal dominant disease of lipid metabolism, which leads to early coronary heart disease. Mutations in LDLR, APOB and PCSK9 can be detected in 80% of definite FH (DFH) patients. This study aimed to identify novel FH-causing genetic variants in patients with no detectable mutation.
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Linkage analysis and exome sequencing identify a novel mutation in KCTD7 in patients with progressive myoclonus epilepsy with ataxia.
Epilepsia
PUBLISHED: 06-17-2014
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Epilepsy affects approximately 1% of the world's population. Genetic factors and acquired etiologies, as well as a range of environmental triggers, together contribute to epileptogenesis. We have identified a family with three daughters affected with progressive myoclonus epilepsy with ataxia. Clinical details of the onset and progression of the neurologic presentation, epileptic seizures, and the natural history of progression over a 10-year period are described. Using autozygosity genetic mapping, we identified a high likelihood homozygous region on chromosome 7p12.1-7q11.22. We subsequently applied whole-exome sequencing and employed a rare variant prioritization analysis within the homozygous region. We identified p.Tyr276Cys in the potassium channel tetramerization domain-containing seven gene, KCTD7, which is expressed predominantly in the brain. Mutations in this gene have been implicated previously in epileptic phenotypes due to disturbances in potassium channel conductance. Pathogenicity of the mutation was supported by bioinformatic predictive analyses and variant cosegregation within the family. Further biologic validation is necessary to fully characterize the pathogenic mechanisms that explain the phenotypic causes of epilepsy with ataxia in these patients.
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Exome sequencing: new insights into lipoprotein disorders.
Curr Cardiol Rep
PUBLISHED: 06-05-2014
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Several next generation sequencing platforms allow for a DNA-to-diagnosis protocol to identify the molecular basis of monogenic dyslipidemias. However, recent reports of the application of whole genome or whole exome sequencing in families with severe dyslipidemias have largely identified genetic variants in known lipid genes. To date, high-throughput DNA sequencing in families with previously uncharacterized monogenic dyslipidemias, have failed to reveal new genes for regulation of plasma lipids. This suggests that rather than sequencing whole genomes or exomes, most patients with monogenic dyslipidemias could be diagnosed using a more dedicated approach that focuses primarily on genes already known to act within lipoprotein metabolic pathways.
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Inheritance of rare functional GCKR variants and their contribution to triglyceride levels in families.
Hum. Mol. Genet.
PUBLISHED: 05-30-2014
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Significant resources have been invested in sequencing studies to investigate the role of rare variants in complex disease etiology. However, the diagnostic interpretation of individual rare variants remains a major challenge, and may require accurate variant functional classification and the collection of large numbers of variant carriers. Utilizing sequence data from 458 individuals with hypertriglyceridemia and 333 controls with normal plasma triglyceride levels, we investigated these issues using GCKR, encoding glucokinase regulatory protein. Eighteen rare non-synonymous GCKR variants identified in these 791 individuals were comprehensively characterized by a range of biochemical and cell biological assays, including a novel high-throughput-screening-based approach capable of measuring all variant proteins simultaneously. Functionally deleterious variants were collectively associated with hypertriglyceridemia, but a range of in silico prediction algorithms showed little consistency between algorithms and poor agreement with functional data. We extended our study by obtaining sequence data on family members; however, functional variants did not co-segregate with triglyceride levels. Therefore, despite evidence for their collective functional and clinical relevance, our results emphasize the low predictive value of rare GCKR variants in individuals and the complex heritability of lipid traits.
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Simple genetics language as source of miscommunication between genetics researchers and potential research participants in informed consent documents.
Public Underst Sci
PUBLISHED: 04-23-2014
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Informed consent is based on communication, requiring language to convey meanings and ensure understandings. The purpose of this study was to investigate the use of language in informed consent documents used in the genetics research funded by Canadian Institutes of Health Research and Genome Canada. Consent documents were requested from the principal investigators in a recent round of funding. A qualitative content analysis was performed, supported by NVivo7™. Potential barriers to informed consent were identified, including language that was vague and variable, words with both technical and common meanings, novel phrases without clear meaning, a lack of definitions, and common concepts that assume new definitions in genetics research. However, we noted that difficulties in comprehension were often obscured because the words used were generally simple and familiar. We conclude that language gaps between researcher and potential research participants may unintentionally impair comprehension and ultimately impair informed consent in genomics research.
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N-of-1 (single-patient) trials for statin-related myalgia.
Ann. Intern. Med.
PUBLISHED: 04-17-2014
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Statin-related myalgia is difficult to distinguish from other conditions causing myalgia and may often lead to statin discontinuation.
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The polygenic nature of hypertriglyceridaemia: implications for definition, diagnosis, and management.
Lancet Diabetes Endocrinol
PUBLISHED: 04-16-2014
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Plasma triglyceride concentration is a biomarker for circulating triglyceride-rich lipoproteins and their metabolic remnants. Common mild-to-moderate hypertriglyceridaemia is typically multigenic, and results from the cumulative burden of common and rare variants in more than 30 genes, as quantified by genetic risk scores. Rare autosomal recessive monogenic hypertriglyceridaemia can result from large-effect mutations in six different genes. Hypertriglyceridaemia is exacerbated by non-genetic factors. On the basis of recent genetic data, we redefine the disorder into two states: severe (triglyceride concentration >10 mmol/L), which is more likely to have a monogenic cause; and mild-to-moderate (triglyceride concentration 2-10 mmol/L). Because of clustering of susceptibility alleles and secondary factors in families, biochemical screening and counselling for family members is essential, but routine genetic testing is not warranted. Treatment includes management of lifestyle and secondary factors, and pharmacotherapy. In severe hypertriglyceridaemia, intervention is indicated because of pancreatitis risk; in mild-to-moderate hypertriglyceridaemia, intervention can be indicated to prevent cardiovascular disease, dependent on triglyceride concentration, concomitant lipoprotein disturbances, and overall cardiovascular risk.
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LipidSeq: a next-generation clinical resequencing panel for monogenic dyslipidemias.
J. Lipid Res.
PUBLISHED: 02-06-2014
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We report the design of a targeted resequencing panel for monogenic dyslipidemias, LipidSeq, for the purpose of replacing Sanger sequencing in the clinical detection of dyslipidemia-causing variants. We also evaluate the performance of the LipidSeq approach versus Sanger sequencing in 84 patients with a range of phenotypes including extreme blood lipid concentrations as well as additional dyslipidemias and related metabolic disorders. The panel performs well, with high concordance (95.2%) in samples with known mutations based on Sanger sequencing and a high detection rate (57.9%) of mutations likely to be causative for disease in samples not previously sequenced. Clinical implementation of LipidSeq has the potential to aid in the molecular diagnosis of patients with monogenic dyslipidemias with a high degree of speed and accuracy and at lower cost than either Sanger sequencing or whole exome sequencing. Furthermore, LipidSeq will help to provide a more focused picture of monogenic and polygenic contributors that underlie dyslipidemia while excluding the discovery of incidental pathogenic clinically actionable variants in nonmetabolism-related genes, such as oncogenes, that would otherwise be identified by a whole exome approach, thus minimizing potential ethical issues.
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Exome sequencing identifies NFS1 deficiency in a novel Fe-S cluster disease, infantile mitochondrial complex II/III deficiency.
Mol Genet Genomic Med
PUBLISHED: 02-06-2014
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Iron-sulfur (Fe-S) clusters are a class of highly conserved and ubiquitous prosthetic groups with unique chemical properties that allow the proteins that contain them, Fe-S proteins, to assist in various key biochemical pathways. Mutations in Fe-S proteins often disrupt Fe-S cluster assembly leading to a spectrum of severe disorders such as Friedreich's ataxia or iron-sulfur cluster assembly enzyme (ISCU) myopathy. Herein, we describe infantile mitochondrial complex II/III deficiency, a novel autosomal recessive mitochondrial disease characterized by lactic acidemia, hypotonia, respiratory chain complex II and III deficiency, multisystem organ failure and abnormal mitochondria. Through autozygosity mapping, exome sequencing, in silico analyses, population studies and functional tests, we identified c.215G>A, p.Arg72Gln in NFS1 as the likely causative mutation. We describe the first disease in man likely caused by deficiency in NFS1, a cysteine desulfurase that is implicated in respiratory chain function and iron maintenance by initiating Fe-S cluster biosynthesis. Our results further demonstrate the importance of sufficient NFS1 expression in human physiology.
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Mining the genome for lipid genes.
Biochim. Biophys. Acta
PUBLISHED: 02-05-2014
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Mining of the genome for lipid genes has since the early 1970s helped to shape our understanding of how triglycerides are packaged (in chylomicrons), repackaged (in very low density lipoproteins; VLDL), and hydrolyzed, and also how remnant and low-density lipoproteins (LDL) are cleared from the circulation. Gene discoveries have also provided insights into high-density lipoprotein (HDL) biogenesis and remodeling. Interestingly, at least half of these key molecular genetic studies were initiated with the benefit of prior knowledge of relevant proteins. In addition, multiple important findings originated from studies in mouse, and from other types of non-genetic approaches. Although it appears by now that the main lipid pathways have been uncovered, and that only modulators or adaptor proteins such as those encoded by LDLRAP1, APOA5, ANGPLT3/4, and PCSK9 are currently being discovered, genome wide association studies (GWAS) in particular have implicated many new loci based on statistical analyses; these may prove to have equally large impacts on lipoprotein traits as gene products that are already known. On the other hand, since 2004 - and particularly since 2010 when massively parallel sequencing has become de rigeur - no major new insights into genes governing lipid metabolism have been reported. This is probably because the etiologies of true Mendelian lipid disorders with overt clinical complications have been largely resolved. In the meantime, it has become clear that proving the importance of new candidate genes is challenging. This could be due to very low frequencies of large impact variants in the population. It must further be emphasized that functional genetic studies, while necessary, are often difficult to accomplish, making it hazardous to upgrade a variant that is simply associated to being definitively causative. Also, it is clear that applying a monogenic approach to dissect complex lipid traits that are mostly of polygenic origin is the wrong way to proceed. The hope is that large-scale data acquisition combined with sophisticated computerized analyses will help to prioritize and select the most promising candidate genes for future research. We suggest that at this point in time, investment in sequence technology driven candidate gene discovery could be recalibrated by refocusing efforts on direct functional analysis of the genes that have already been discovered. This article is part of a Special Issue entitled: From Genome to Function.
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The 2014 Canadian Hypertension Education Program recommendations for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension.
Can J Cardiol
PUBLISHED: 01-23-2014
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Herein, updated evidence-based recommendations for the diagnosis, assessment, prevention, and treatment of hypertension in Canadian adults are detailed. For 2014, 3 existing recommendations were modified and 2 new recommendations were added. The following recommendations were modified: (1) the recommended sodium intake threshold was changed from ? 1500 mg (3.75 g of salt) to approximately 2000 mg (5 g of salt) per day; (2) a pharmacotherapy treatment initiation systolic blood pressure threshold of ? 160 mm Hg was added in very elderly (age ? 80 years) patients who do not have diabetes or target organ damage (systolic blood pressure target in this population remains at < 150 mm Hg); and (3) the target population recommended to receive low-dose acetylsalicylic acid therapy for primary prevention was narrowed from all patients with controlled hypertension to only those ? 50 years of age. The 2 new recommendations are: (1) advice to be cautious when lowering systolic blood pressure to target levels in patients with established coronary artery disease if diastolic blood pressure is ? 60 mm Hg because of concerns that myocardial ischemia might be exacerbated; and (2) the addition of glycated hemoglobin (A1c) in the diagnostic work-up of patients with newly diagnosed hypertension. The rationale for these recommendation changes is discussed. In addition, emerging data on blood pressure targets in stroke patients are discussed; these data did not lead to recommendation changes at this time. The Canadian Hypertension Education Program recommendations will continue to be updated annually.
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Validation of volumetric and single-slice MRI adipose analysis using a novel fully automated segmentation method.
J Magn Reson Imaging
PUBLISHED: 01-17-2014
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To validate a fully automated adipose segmentation method with magnetic resonance imaging (MRI) fat fraction abdominal imaging. We hypothesized that this method is suitable for segmentation of subcutaneous adipose tissue (SAT) and intra-abdominal adipose tissue (IAAT) in a wide population range, easy to use, works with a variety of hardware setups, and is highly repeatable.
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Gene-centric meta-analyses for central adiposity traits in up to 57,412 individuals of European descent confirm known loci and reveal several novel associations.
Hum. Mol. Genet.
PUBLISHED: 12-17-2013
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Waist circumference (WC) and waist-to-hip ratio (WHR) are surrogate measures of central adiposity that are associated with adverse cardiovascular events, type 2 diabetes, and cancer independent of body mass index (BMI). WC and WHR are highly heritable with multiple susceptibility loci identified to date. We assessed the association between SNPs and BMI-adjusted WC and WHR and unadjusted WC in up to 57,412 individuals of European descent from 22 cohorts collaborating with the NHLBIs Candidate Gene Association Resource (CARe) project. The study population consisted of women and men aged 20 to 80. Study participants were genotyped using the ITMAT/Broad/CARE array, which includes ?50,000 cosmopolitan tagged SNPs across ?2,100 cardiovascular-related genes. Each trait was modeled as a function of age, study site, and principal components to control for population stratification, and we conducted a fixed-effects meta-analysis. No new loci for WC were observed. For WHR analyses, three novel loci were significantly associated (P<2.4x10(-6)). Previously unreported rs2811337-G near TMCC1 was associated with increased WHR (?±SE,0.048±0.008, P=7.7x10(-9)) as was rs7302703-G in HOXC10 (?=0.044±0.008, P=2.9x10(-7)) and rs936108-C in PEMT (?=0.035±0.007, P=1.9x10(-6)). Sex-stratified analyses revealed two additional novel signals among females only, rs12076073-A near SHC1 (?=0.10±0.02, P=1.9x10(-6)), and rs1037575-A in ATBDB4 (?=0.046±0.01, P=2.2x10(-6)), supporting an already established sexual dimorphism of central adiposity-related genetic variants. Functional analysis using ENCODE and eQTL databases revealed that several of these loci are in regulatory regions or regions with differential expression in adipose tissue.
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Diagnosis, prevention, and management of statin adverse effects and intolerance: canadian working group consensus update.
Can J Cardiol
PUBLISHED: 09-18-2013
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The Proceedings of a Canadian Working Group Consensus Conference, first published in 2011, provided a summary of statin-associated adverse effects and intolerance and management suggestions. In this update, new clinical studies identified since then that provide further insight into effects on muscle, cognition, cataracts, diabetes, kidney disease, and cancer are discussed. Of these, the arenas of greatest controversy pertain to purported effects on cognition and the emergence of diabetes during long-term therapy. Regarding cognition, the available evidence is not strongly supportive of a major adverse effect of statins. In contrast, the linkage between statin therapy and incident diabetes is more firm. However, this risk is more strongly associated with traditional risk factors for new-onset diabetes than with statin itself and any possible negative effect of new-onset diabetes during statin treatment is far outweighed by the cardiovascular risk reduction benefits. Additional studies are also discussed, which support the principle that systematic statin rechallenge, and lower or intermittent statin dosing strategies are the main methods for dealing with suspected statin intolerance at this time.
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Abetalipoproteinemia and homozygous hypobetalipoproteinemia: a framework for diagnosis and management.
J. Inherit. Metab. Dis.
PUBLISHED: 09-16-2013
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Abetalipoproteinemia (ABL; OMIM 200100) and homozygous hypobetalipoproteinemia (HHBL; OMIM 107730) are rare diseases characterized by hypocholesterolemia and malabsorption of lipid-soluble vitamins leading to retinal degeneration, neuropathy and coagulopathy. Hepatic steatosis is also common. The root cause of both disorders is improper packaging and secretion of apolipoprotein (apo) B-containing lipoprotein particles due to mutations either in both alleles of the MTP (alias MTTP) gene encoding microsomal triglyceride transfer protein (MTP) or both alleles of the APOB gene itself in the case of ABL and HHBL, respectively. Clinical diagnosis is based on signs and symptoms, acanthocytosis on blood smear, and virtually absent apo B-containing lipoproteins, including chylomicrons, very low density lipoprotein and low density lipoprotein. Obligate heterozygote parents of ABL patients usually have normal lipids consistent with autosomal recessive inheritance, while heterozygous parents of HHBL patients typically have half normal levels of apo B-containing lipoproteins consistent with autosomal co-dominant inheritance. Definitive diagnosis involves sequencing the MTP and APOB genes, for which >30 and >60 mutations have been described for ABL and HHBL, respectively. Follow-up includes monitoring for ophthalmologic, neurologic, hematologic, and hepatic complications, as well as compliance with treatment. Investigations include lipid profile, serum transaminases, markers for lipid-soluble vitamins, and periodic instrumental assessment of ocular and neurological function. Mainstays of treatment include adherence to a low-fat diet, and supplementation with essential fatty acids and high oral doses of fat soluble vitamins. Prognosis is variable, but early diagnosis and strict adherence to treatment can recover normal neurological function and halt disease progression.
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Current Phase II proprotein convertase subtilisin/kexin 9 inhibitor therapies for dyslipidemia.
Expert Opin Investig Drugs
PUBLISHED: 07-26-2013
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Reduction of plasma low-density lipoprotein (LDL) cholesterol concentration with statins reduces adverse cardiovascular outcomes. However, lack of efficacy and intolerance of statins in many patients requires alternative treatments. Currently available non-statin alternatives include bile acid sequestrants, the cholesterol absorption inhibitor ezetimibe, niacin-based preparations and fibrates; however, each of these has limitations. Newer agents for LDL cholesterol reduction include the cholesterol ester transfer protein inhibitors, the microsomal triglyceride transfer protein inhibitor lomitapide, the apolipoprotein B antisense oligonucleotide mipomersen and several molecules that inhibit or interfere with proprotein convertase subtilisin/kexin 9 (PCSK9).
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Clinical and pharmacogenetic predictors of circulating atorvastatin and rosuvastatin concentrations in routine clinical care.
Circ Cardiovasc Genet
PUBLISHED: 07-22-2013
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A barrier to statin therapy is myopathy associated with elevated systemic drug exposure. Our objective was to examine the association between clinical and pharmacogenetic variables and statin concentrations in patients.
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Incremental lowering of low-density lipoprotein cholesterol with ezetimibe 20 mg vs 10 mg daily in patients receiving concomitant statin therapy.
Can J Cardiol
PUBLISHED: 07-16-2013
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Ezetimibe is typically administered at a dose of 10 mg daily, with few reports of use at other doses. We compared plasma concentrations of low-density lipoprotein (LDL) cholesterol and other lipid variables in patients with dyslipidemia who were receiving ezetimibe 10 mg and then 20 mg daily.
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APOE p.Leu167del mutation in familial hypercholesterolemia.
Atherosclerosis
PUBLISHED: 07-15-2013
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Autosomal dominant hypercholesterolemia (ADH) is caused by mutations in the low density lipoprotein receptor (LDLR), its ligand apoB (APOB) or proprotein convertase subtilisin/kexin type 9 (PCSK9) genes. Yet DNA sequencing does not identify mutations in these genes in a significant number of cases, suggesting that ADH has multiple genetic etiologies.
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A mutation in the serine protease TMPRSS4 in a novel pediatric neurodegenerative disorder.
Orphanet J Rare Dis
PUBLISHED: 06-14-2013
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To elucidate the genetic basis of a novel neurodegenerative disorder in an Old Order Amish pedigree by combining homozygosity mapping with exome sequencing.
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Rare APOA5 promoter variants associated with paradoxical HDL cholesterol decrease in response to fenofibric acid therapy.
J. Lipid Res.
PUBLISHED: 04-30-2013
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Individuals with mixed dyslipidemia, including high triglycerides (TGs) and low high density lipoprotein cholesterol (HDL-C), have increased risk for coronary events. We examined the effect of rare genetic variants in the APOA5 gene region on plasma HDL-C, apolipoprotein A-I (apoA-I), and TG response to fenofibric acid monotherapy and in combination with statins. The APOA5 gene region was sequenced in 1,612 individuals with mixed dyslipidemia in a randomized trial of fenofibric acid alone and in combination with statins. Students t-test and rare variant burden tests were used to examine plasma HDL-C, apoA-I, and TG response. Rare APOA5 promoter region variants were associated with decreased HDL-C and apoA-I levels in response to fenofibric acid therapy; rare missense variants were associated with increased TG response to combination therapy. Further study is needed to examine the effect of these rare variants on coronary outcomes in this population in response to fenofibric acid monotherapy or combined with statins.
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Infantile Sialic Acid Storage Disease: Two Unrelated Inuit Cases Homozygous for a Common Novel SLC17A5 Mutation.
JIMD Rep
PUBLISHED: 04-12-2013
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Infantile sialic acid storage disease (ISSD) is a lysosomal storage disease characterized by accumulation of covalently unlinked (free) sialic acid in multiple tissues. ISSD and Salla disease (a predominantly neurological disorder) are allelic disorders caused by recessive mutations of a lysosomal anionic monosaccharide transporter, SLC17A5. While Salla disease is common in Finland due to a founder-effect mutation (p.Arg39Cys), ISSD is comparatively rare in all populations studied.Here, we describe the clinical and molecular features of two unrelated Canadian Inuit neonates with a virtually identical presentation of ISSD. Both individuals presented antenatally with fetal hydrops, dying shortly following delivery. Urinary free sialic acid excretion was markedly increased in the one case in which urine could be obtained for testing; postmortem examination showed a picture of widespread lysosomal storage in both. Both children were homozygous for a novel splice site mutation (NM_012434:c.526-2A>G) resulting in skipping of exon 4 and an ensuing frameshift. Analysis of a further 129 pan-Arctic Inuit controls demonstrated a heterozygous carrier rate of 1/129 (~0.4 %) in our sample. Interestingly, lysosomal enzyme studies showed an unexplained ninefold increase in neuraminidase activity, with lesser elevations in the activities of several other lysosomal enzymes. Our results raise the possibility of a common founder mutation presenting as hydrops in this population. Furthermore, if confirmed in subsequent cases, the marked induction of neuraminidase activity seen here may prove useful in the clinical diagnosis of ISSD.
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Recessive TRAPPC11 mutations cause a disease spectrum of limb girdle muscular dystrophy and myopathy with movement disorder and intellectual disability.
Am. J. Hum. Genet.
PUBLISHED: 03-19-2013
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Myopathies are a clinically and etiologically heterogeneous group of disorders that can range from limb girdle muscular dystrophy (LGMD) to syndromic forms with associated features including intellectual disability. Here, we report the identification of mutations in transport protein particle complex 11 (TRAPPC11) in three individuals of a consanguineous Syrian family presenting with LGMD and in five individuals of Hutterite descent presenting with myopathy, infantile hyperkinetic movements, ataxia, and intellectual disability. By using a combination of whole-exome or genome sequencing with homozygosity mapping, we identified the homozygous c.2938G>A (p.Gly980Arg) missense mutation within the gryzun domain of TRAPPC11 in the Syrian LGMD family and the homozygous c.1287+5G>A splice-site mutation resulting in a 58 amino acid in-frame deletion (p.Ala372_Ser429del) in the foie gras domain of TRAPPC11 in the Hutterite families. TRAPPC11 encodes a component of the multiprotein TRAPP complex involved in membrane trafficking. We demonstrate that both mutations impair the binding ability of TRAPPC11 to other TRAPP complex components and disrupt the Golgi apparatus architecture. Marker trafficking experiments for the p.Ala372_Ser429del deletion indicated normal ER-to-Golgi trafficking but dramatically delayed exit from the Golgi to the cell surface. Moreover, we observed alterations of the lysosomal membrane glycoproteins lysosome-associated membrane protein 1 (LAMP1) and LAMP2 as a consequence of TRAPPC11 dysfunction supporting a defect in the transport of secretory proteins as the underlying pathomechanism.
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Efficacy and plasma drug concentrations with nondaily dosing of rosuvastatin.
Can J Cardiol
PUBLISHED: 03-05-2013
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Nondaily statin dosing is an alternative for patients unable to tolerate daily dosing. The higher potency and longer half-life of rosuvastatin lends itself to this regimen. The basis of this improved tolerability is not understood, but might be related to lower plasma drug concentrations. We examined the efficacy of nondaily rosuvastatin in previously statin-intolerant patients and determined plasma drug concentrations at various dose regimens.
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Omega-3 fatty acids, polymorphisms and lipid related cardiovascular disease risk factors in the Inuit population.
Nutr Metab (Lond)
PUBLISHED: 03-03-2013
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Tissue concentrations of fatty acids (FAs) and genetic variations are well-known factors which affect the cardiovascular disease (CVD) risk. The objective was to examine whether the genetic variability of 20 candidate genes and red blood cells (RBCs) percentage of total n-3 polyunsaturated fatty acids (PUFA), a biomarker of dietary n-3 PUFA intake, modulate lipid related CVD risk factors in the Inuit population.
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Intellectual disability associated with a homozygous missense mutation in THOC6.
Orphanet J Rare Dis
PUBLISHED: 02-12-2013
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BACKGROUND: We recently described a novel autosomal recessive neurodevelopmental disorder with intellectual disability in four patients from two related Hutterite families. Identity-by-descent mapping localized the gene to a 5.1 Mb region at chromosome 16p13.3 containing more than 170 known or predicted genes. The objective of this study was to identify the causative gene for this rare disorder.Methods and results: Candidate gene sequencing followed by exome sequencing identified a homozygous missense mutation p. Gly46Arg, in THOC6. No other potentially causative coding variants were present within the critical region on chromosome 16. THOC6 is a member of the THO/TREX complex which is involved in coordinating mRNA processing with mRNA export from the nucleus. In situ hybridization showed that thoc6 is highly expressed in the midbrain and eyes. Cellular localization studies demonstrated that wild-type THOC6 is present within the nucleus as is the case for other THO complex proteins. However, mutant THOC6 was predominantly localized in the cytoplasm, suggesting that the mutant protein is unable to carry out its normal function. siRNA knockdown of THOC6 revealed increased apoptosis in cultured cells. CONCLUSION: Our findings associate a missense mutation in THOC6 with intellectual disability, suggesting the THO/TREX complex plays an important role in neurodevelopment.
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2012 update of the Canadian Cardiovascular Society guidelines for the diagnosis and treatment of dyslipidemia for the prevention of cardiovascular disease in the adult.
Can J Cardiol
PUBLISHED: 01-29-2013
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Many developments have occurred since the publication of the widely-used 2009 Canadian Cardiovascular Society (CCS) Dyslipidemia guidelines. Here, we present an updated version of the guidelines, incorporating new recommendations based on recent findings and harmonizing CCS guidelines with those from other Societies. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used, per present standards of the CCS. The total cardiovascular disease Framingham Risk Score (FRS), modified for a family history of premature coronary disease, is recommended for risk assessment. Low-density lipoprotein cholesterol remains the primary target of therapy. However, non-high density lipoprotein cholesterol has been added to apolipoprotein B as an alternate target. There is an increased emphasis on treatment of higher risk patients, including those with chronic kidney disease and high risk hypertension. The primary panel has recommended a judicious use of secondary testing for subjects in whom the need for statin therapy is unclear. Expanded information on health behaviours is presented and is the backbone of risk reduction in all subjects. Finally, a systematic approach to statin intolerance is advocated to maximize appropriate use of lipid-lowering therapy. This document presents the recommendations and principal conclusions of this process. Along with associated Supplementary Material that can be accessed online, this document will be part of a program of knowledge translation. The goal is to increase the appropriate use of evidence-based cardiovascular disease event risk assessment in the management of dyslipidemia as a fundamental means of reducing global risk in the Canadian population.
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Hypertriglyceridemia.
Nutrients
PUBLISHED: 01-22-2013
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Hypertriglyceridemia (HTG) is commonly encountered in lipid and cardiology clinics. Severe HTG warrants treatment because of the associated increased risk of acute pancreatitis. However, the need to treat, and the correct treatment approach for patients with mild to moderate HTG are issues for ongoing evaluation. In the past, it was felt that triglyceride does not directly contribute to development of atherosclerotic plaques. However, this view is evolving, especially for triglyceride-related fractions and variables measured in the non-fasting state. Our understanding of the etiology, genetics and classification of HTG states is also evolving. Previously, HTG was considered to be a dominant disorder associated with variation within a single gene. The old nomenclature includes the term "familial" in the names of several hyperlipoproteinemia (HLP) phenotypes that included HTG as part of their profile, including combined hyperlipidemia (HLP type 2B), dysbetalipoproteinemia (HLP type 3), simple HTG (HLP type 4) and mixed hyperlipidemia (HLP type 5). This old thinking has given way to the idea that genetic susceptibility to HTG results from cumulative effects of multiple genetic variants acting in concert. HTG most is often a "polygenic" or "multigenic" trait. However, a few rare autosomal recessive forms of severe HTG have been defined. Treatment depends on the overall clinical context, including severity of HTG, concomitant presence of other lipid disturbances, and the patients global risk of cardiovascular disease. Therapeutic strategies include dietary counselling, lifestyle management, control of secondary factors, use of omega-3 preparations and selective use of pharmaceutical agents.
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Western Database of Lipid Variants (WDLV): a catalogue of genetic variants in monogenic dyslipidemias.
Can J Cardiol
PUBLISHED: 01-16-2013
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Next-generation sequencing (NGS) is nearing routine clinical application, especially for diagnosis of rare monogenic cardiovascular diseases. But NGS uncovers so much variation in an individual genome that filtering steps are required to streamline data management. The first step is to determine whether a potential disease-causing variant has been observed previously in affected patients.
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HDL--is it too big to fail?
Nat Rev Endocrinol
PUBLISHED: 01-15-2013
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The HDL hypothesis has suffered damage in the past few years. Clinical trials have shown that raising HDL cholesterol levels does not improve cardiovascular disease (CVD) outcomes. In addition, Mendelian randomization studies have shown that DNA variants that alter HDL cholesterol levels in populations are unrelated to incident CVD events. Balancing this deluge of negative data are substantial basic science data supporting the concept that raising HDL cholesterol levels reduces CVD risk. Also, functionally relevant HDL subfractions might be more important determinants of risk than overall HDL cholesterol levels. But, while wobbly, the HDL hypothesis is still standing, seemingly too big to fail owing to past intellectual, economic and psychological investments in the idea.
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The 2013 Canadian Hypertension Education Program recommendations for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension.
Can J Cardiol
PUBLISHED: 01-12-2013
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We updated the evidence-based recommendations for the diagnosis, assessment, prevention, and treatment of hypertension in adults for 2013. This years update includes 2 new recommendations. First, among nonhypertensive or stage 1 hypertensive individuals, the use of resistance or weight training exercise does not adversely influence blood pressure (BP) (Grade D). Thus, such patients need not avoid this type of exercise for fear of increasing BP. Second, and separately, for very elderly patients with isolated systolic hypertension (age 80 years or older), the target for systolic BP should be < 150 mm Hg (Grade C) rather than < 140 mm Hg as recommended for younger patients. We also discuss 2 additional topics at length (the pharmacological treatment of mild hypertension and the possibility of a diastolic J curve in hypertensive patients with coronary artery disease). In light of several methodological limitations, a recent systematic review of 4 trials in patients with stage 1 uncomplicated hypertension did not lead to changes in management recommendations. In addition, because of a lack of prospective randomized data assessing diastolic BP thresholds in patients with coronary artery disease and hypertension, no recommendation to set a selective diastolic cut point for such patients could be affirmed. However, both of these issues will be examined on an ongoing basis, in particular as new evidence emerges.
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Homozygous lamin A/C familial lipodystrophy R482Q mutation in autosomal recessive Emery Dreifuss muscular dystrophy.
Neuromuscul. Disord.
PUBLISHED: 01-11-2013
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Autosomal recessive Emery Dreifuss muscular dystrophy (AR-EDMD) is rare, with few reports in the medical literature. We describe the first cases of AR-EDMD and autosomal dominant familial partial lipodystrophy (FPLD) in the Hutterite population resulting from homozygous or heterozygous R482Q mutations in the lamin A/C gene (LMNA). Heterozygosity for LMNA R482Q mutation causes FPLD, which is associated with increased risk of hyperlipidemia and hypertension. The overall carrier frequency of the R482Q mutation in Dariusleut and Leherleut Hutterites in Alberta was found to be 1.45%. Homozygosity for this mutation has not been previously reported and here resulted in a combination of generalized lipodystrophy and EDMD. Knowledge that the LMNA R482Q mutation is present in this population is important for genetic counseling, surveillance, and management of the associated disorders.
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Detection of a novel frameshift mutation and regions with homozygosis within ARHGEF28 gene in familial amyotrophic lateral sclerosis.
Amyotroph Lateral Scler Frontotemporal Degener
PUBLISHED: 01-04-2013
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Rho guanine nucleotide exchange factor (RGNEF) is a novel NFL mRNA destabilizing factor that forms neuronal cytoplasmic inclusions in spinal motor neurons in both sporadic (SALS) and familial (FALS) ALS patients. Given the observation of genetic mutations in a number of mRNA binding proteins associated with ALS, including TDP-43, FUS/TLS and mtSOD1, we analysed the ARHGEF28 gene (approx. 316 kb) that encodes for RGNEF in FALS cases to determine if mutations were present. We performed genomic sequencing, copy number variation analysis using TaqMan real-time PCR and spinal motor neuron immunohistochemistry using a novel RGNEF antibody. In this limited sample of FALS cases (n=7) we identified a heterozygous mutation that is predicted to generate a premature truncated gene product. We also observed extensive regions of homozygosity in the ARHGEF28 gene in two FALS patients. In conclusion, our findings of genetic alterations in the ARHGEF28 gene in cases of FALS suggest that a more comprehensive genetic analysis would be warranted.
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Causal relationship between adiponectin and metabolic traits: a Mendelian randomization study in a multiethnic population.
PLoS ONE
PUBLISHED: 01-01-2013
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Adiponectin, a secretagogue exclusively produced by adipocytes, has been associated with metabolic features, but its role in the development of the metabolic syndrome remains unclear.
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Excess of rare variants in non-genome-wide association study candidate genes in patients with hypertriglyceridemia.
Circ Cardiovasc Genet
PUBLISHED: 12-01-2011
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Rare variant accumulation studies can implicate genes in disease susceptibility when a significant burden is observed in patients versus control subjects. Such analyses might be particularly useful for candidate genes that are selected based on experiments other than genome-wide association studies (GWAS). We sought to determine whether rare variants in non-GWAS candidate genes identified from mouse models and human mendelian syndromes of hypertriglyceridemia (HTG) accumulate in patients with polygenic adult-onset HTG.
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TMEM237 is mutated in individuals with a Joubert syndrome related disorder and expands the role of the TMEM family at the ciliary transition zone.
Am. J. Hum. Genet.
PUBLISHED: 08-26-2011
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Joubert syndrome related disorders (JSRDs) have broad but variable phenotypic overlap with other ciliopathies. The molecular etiology of this overlap is unclear but probably arises from disrupting common functional module components within primary cilia. To identify additional module elements associated with JSRDs, we performed homozygosity mapping followed by next-generation sequencing (NGS) and uncovered mutations in TMEM237 (previously known as ALS2CR4). We show that loss of the mammalian TMEM237, which localizes to the ciliary transition zone (TZ), results in defective ciliogenesis and deregulation of Wnt signaling. Furthermore, disruption of Danio rerio (zebrafish) tmem237 expression produces gastrulation defects consistent with ciliary dysfunction, and Caenorhabditis elegans jbts-14 genetically interacts with nphp-4, encoding another TZ protein, to control basal body-TZ anchoring to the membrane and ciliogenesis. Both mammalian and C. elegans TMEM237/JBTS-14 require RPGRIP1L/MKS5 for proper TZ localization, and we demonstrate additional functional interactions between C. elegans JBTS-14 and MKS-2/TMEM216, MKSR-1/B9D1, and MKSR-2/B9D2. Collectively, our findings integrate TMEM237/JBTS-14 in a complex interaction network of TZ-associated proteins and reveal a growing contribution of a TZ functional module to the spectrum of ciliopathy phenotypes.
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Evaluation of adipose tissue volume quantification with IDEAL fat-water separation.
J Magn Reson Imaging
PUBLISHED: 07-23-2011
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To validate iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) for adipose tissue volume quantification. IDEAL allows MRI images to be produced only from adipose-containing tissues; hence, quantifying adipose tissue should be simpler and more accurate than with current methods.
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Transcriptional profiling of endocrine cerebro-osteodysplasia using microarray and next-generation sequencing.
PLoS ONE
PUBLISHED: 06-27-2011
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Transcriptome profiling of patterns of RNA expression is a powerful approach to identify networks of genes that play a role in disease. To date, most mRNA profiling of tissues has been accomplished using microarrays, but next-generation sequencing can offer a richer and more comprehensive picture.
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Allelic and phenotypic spectrum of plasma triglycerides.
Biochim. Biophys. Acta
PUBLISHED: 06-07-2011
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The genetic underpinnings of both normal and pathological variation in plasma triglyceride (TG) concentration are relatively well understood compared to many other complex metabolic traits. For instance, genome-wide association studies (GWAS) have revealed 32 common variants that are associated with plasma TG concentrations in healthy epidemiologic populations. Furthermore, GWAS in clinically ascertained hypertriglyceridemia (HTG) patients have shown that almost all of the same TG-raising alleles from epidemiologic samples are also associated with HTG disease status, and that greater accumulation of these alleles reflects the severity of the HTG phenotype. Finally, comprehensive resequencing studies show a burden of rare variants in some of these same genes - namely in LPL, GCKR, APOB and APOA5 - in HTG patients compared to normolipidemic controls. A more complete understanding of the genes and genetic variants associated with plasma TG concentration will enrich our understanding of the molecular pathways that modulate plasma TG metabolism, which may translate into clinical benefit. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.
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An increased burden of common and rare lipid-associated risk alleles contributes to the phenotypic spectrum of hypertriglyceridemia.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 05-19-2011
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Earlier studies have suggested that a common genetic architecture underlies the clinically heterogeneous polygenic Fredrickson hyperlipoproteinemia (HLP) phenotypes defined by hypertriglyceridemia (HTG). Here, we comprehensively analyzed 504 HLP-HTG patients and 1213 normotriglyceridemic controls and confirmed that a spectrum of common and rare lipid-associated variants underlies this heterogeneity.
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Genetic bases of hypertriglyceridemic phenotypes.
Curr. Opin. Lipidol.
PUBLISHED: 04-27-2011
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Hypertriglyceridemia (HTG) is a common diagnosis. Although secondary factors are important for clinical expression, susceptibility to HTG has a strong genetic component, which we review here.
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Sortilin: an unusual suspect in cholesterol metabolism: from GWAS identification to in vivo biochemical analyses, sortilin has been identified as a novel mediator of human lipoprotein metabolism.
Bioessays
PUBLISHED: 04-04-2011
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The concentration of low-density lipoprotein (LDL) cholesterol (C) in plasma is a key determinant of cardiovascular disease risk and human genetic studies have long endeavoured to elucidate the pathways that regulate LDL metabolism. Massive genome-wide association studies (GWASs) of common genetic variation associated with LDL-C in the population have implicated SORT1 in LDL metabolism. Using experimental paradigms and standards appropriate for understanding the mechanisms by which common variants alter phenotypic expression, three recent publications have presented divergent and even contradictory findings. Interestingly, although these reports each linked SORT1 to LDL metabolism, they did not agree on a mechanism to explain the association. Here, we review recent mechanistic studies of SORT1 - the first gene identified by GWAS as a determinant of plasma LDL-C to be evaluated mechanistically.
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Diagnosis, prevention, and management of statin adverse effects and intolerance: proceedings of a Canadian Working Group Consensus Conference.
Can J Cardiol
PUBLISHED: 03-16-2011
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While the proportion of patients with significant statin-associated adverse effects or intolerance is very low, the increasing use and broadening indications have led to a significant absolute number of such patients commonly referred to tertiary care facilities and specialists. This report provides a comprehensive overview of the evidence pertaining to a broad variety of statin-associated adverse effects followed by a consensus approach for the prevention, assessment, diagnosis, and management. The overview is intended both to provide clarification of the untoward effects of statins and to impart confidence in managing the most common issues in a fashion that avoids excessive ancillary testing and/or subspecialty referral except when truly necessary. The ultimate goal is to ensure that patients who warrant cardiovascular risk reduction can be treated optimally, safely, and confidently with statin medications or alternatives when warranted.
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The transcription factor cyclic AMP-responsive element-binding protein H regulates triglyceride metabolism.
Nat. Med.
PUBLISHED: 03-07-2011
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Here we report that the transcription factor cyclic AMP-responsive element-binding protein H (CREB-H, encoded by CREB3L3) is required for the maintenance of normal plasma triglyceride concentrations. CREB-H-deficient mice showed hypertriglyceridemia secondary to inefficient triglyceride clearance catalyzed by lipoprotein lipase (Lpl), partly due to defective expression of the Lpl coactivators Apoc2, Apoa4 and Apoa5 (encoding apolipoproteins C2, A4 and A5, respectively) and concurrent augmentation of the Lpl inhibitor Apoc3. We identified multiple nonsynonymous mutations in CREB3L3 that produced hypomorphic or nonfunctional CREB-H protein in humans with extreme hypertriglyceridemia, implying a crucial role for CREB-H in human triglyceride metabolism.
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The 2011 Canadian Hypertension Education Program recommendations for the management of hypertension: blood pressure measurement, diagnosis, assessment of risk, and therapy.
Can J Cardiol
PUBLISHED: 03-02-2011
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We updated the evidence-based recommendations for the diagnosis, assessment, prevention, and treatment of hypertension in adults for 2011. The major guideline changes this year are: (1) a recommendation was made for using comparative risk analogies when communicating a patients cardiovascular risk; (2) diagnostic testing issues for renal artery stenosis were discussed; (3) recommendations were added for the management of hypertension during the acute phase of stroke; (4) people with hypertension and diabetes are now considered high risk for cardiovascular events if they have elevated urinary albumin excretion, overt kidney disease, cardiovascular disease, or the presence of other cardiovascular risk factors; (5) the combination of an angiotensin-converting enzyme (ACE) inhibitor and a dihydropyridine calcium channel blocker (CCB) is preferred over the combination of an ACE inhibitor and a thiazide diuretic in persons with diabetes and hypertension; and (6) a recommendation was made to coordinate with pharmacists to improve antihypertensive medication adherence. We also discussed the recent analyses that examined the association between angiotensin II receptor blockers (ARBs) and cancer.
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Lipid modification in the elderly using the combination of a statin and a cholesterol absorption inhibitor.
Expert Opin Pharmacother
PUBLISHED: 02-07-2011
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While the optimal lipid-lowering treatment to reduce cardiovascular disease (CVD) risk in elderly patients has not been definitively established, evidence so far indicates that reducing low-density lipoprotein cholesterol (LDL-C) should be a primary goal, as with other patient groups. The VYTELD (VYTorin in the ELDerly) study--a multicenter, 12-week, randomized, double-blind trial--evaluated the efficacy and safety of combination therapy comprised of ezetimibe plus simvastatin (eze/simva) versus atorvastatin in 1289 hypercholesterolemic patients aged ? 65 years. For all prespecified comparisons, patients randomized to eze/simva were found to have significantly greater percentage decreases in LDL-C and were significantly more likely to achieve LDL-C target levels compared with those on atorvastatin monotherapy (p < 0.05 to < 0.001). Also, the proportions of subjects reaching secondary biochemical targets were similarly greater with eze/simva than with atorvastatin monotherapy for all prespecified comparisons (p < 0.01 to < 0.001). Finally, there were no differences in tolerability between the treatments. The authors concluded that in patients aged ? 65 years, the eze/simva combination provided significantly greater improvements in key lipid variables, with a larger proportion of subjects reaching target LDL-C compared with atorvastatin monotherapy. Despite these promising short-term results, the longer-term safety and efficacy of combination treatment across diverse populations requires further evaluation.
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Clinical implications of direct-to-consumer genetic testing for cardiovascular disease risk.
Can J Cardiol
PUBLISHED: 01-11-2011
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Direct-to-consumer (DTC) genetic testing for cardiovascular disease (CVD) is becoming increasingly accessible due to technological advances, falling prices, and assertive marketing. However, information to guide physicians and patients on how to interpret or react clinically to DTC genetic test results is scarce. We report the case of a 52-year-old man with a family history of CVD who had DTC genetic testing performed. We discuss selected results and interpretation of this testing and the outcome of subsequent lifestyle interventions. Despite the information this new technology seemed to provide, traditional advice on lifestyle modification was central to his management.
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HNF1A G319S variant, active cigarette smoking and incident type 2 diabetes in Aboriginal Canadians: a population-based epidemiological study.
BMC Med. Genet.
PUBLISHED: 01-05-2011
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In a recent report of large-scale association analysis, a type 2 diabetes susceptibility locus near HNF1A was identified in predominantly European descent populations. A population-specific G319S polymorphism in HNF1A was previously identified in Aboriginal Canadians who have a high prevalence of type 2 diabetes. We aimed to investigate the association of the HNF1A G319S polymorphism with incident type 2 diabetes and to assess whether clinical risk variables for type 2 diabetes influence the association in an Aboriginal population.
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Genetic risk factors for stroke in the genome-wide association era.
Expert Opin Med Diagn
PUBLISHED: 01-01-2011
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Importance of the field: Recent genome-wide association studies (GWASs) have renewed interest in genetic determinants of a wide range of complex traits and disorders, including stroke. Areas covered in this review: This paper reviews the current knowledge of genes that contribute to rare monogenic forms of stroke as well as more common garden variety forms, focusing on the results of GWASs. Potential clinical pharmacogenetic and diagnostic applications of this information are considered. Publications from 1990 to September 2010 were identified through a Medline search using terms human stroke and genetics, monogenic, familial, mutation, genome-wide association study, polymorphism, or genotype. What the reader will gain: The review synthesizes and collates the current understanding of genes that are involved across a range of stroke subphenotypes. Take home message: The complexity of stroke will make translation of genetic findings into new diagnostic or therapeutic tools relatively more challenging than for some other conditions and tempers the authors enthusiasm for the eventual clinical utility of this information.
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A translational view of the genetics of lipodystrophy and ectopic fat deposition.
Prog Mol Biol Transl Sci
PUBLISHED: 11-02-2010
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A wide range of lipodystrophy syndromes exist, each with varying clinical presentations, and yet cumulatively they underscore the importance of adipocyte biology in human metabolism. Loss of the ability to retain excess lipids in "classical" adipose tissue stores can lead to the overdevelopment of ectopic fat stores, often creating severe perturbations of both glucose and lipid homeostasis. Linkage analysis and candidate sequencing efforts have successfully identified responsible mutations for multiple forms of lipodystrophy. Recently, the reduction in the cost of DNA sequencing has resulted in discovery of many novel mutations within both known and novel loci. In this review, we present the steps involved in clinical characterization of a suspected lipodystrophy case, an overview of the clinical manifestations, molecular findings, and pathogenic basis of different forms of lipodystrophy, a discussion of therapeutic options for lipodystrophy patients, and an examination of genetic advances that will be used to identify additional pathogenic mechanisms.
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Genetic determinants of plasma triglycerides.
J. Lipid Res.
PUBLISHED: 11-01-2010
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Plasma triglyceride (TG) concentration is reemerging as an important cardiovascular disease risk factor. More complete understanding of the genes and variants that modulate plasma TG should enable development of markers for risk prediction, diagnosis, prognosis, and response to therapies and might help specify new directions for therapeutic interventions. Recent genome-wide association studies (GWAS) have identified both known and novel loci associated with plasma TG concentration. However, genetic variation at these loci explains only ?10% of overall TG variation within the population. As the GWAS approach may be reaching its limit for discovering genetic determinants of TG, alternative genetic strategies, such as rare variant sequencing studies and evaluation of animal models, may provide complementary information to flesh out knowledge of clinically and biologically important pathways in TG metabolism. Herein, we review genes recently implicated in TG metabolism and describe how some of these genes likely modulate plasma TG concentration. We also discuss lessons regarding plasma TG metabolism learned from various genomic and genetic experimental approaches. Treatment of patients with moderate to severe hypertriglyceridemia with existing therapies is often challenging; thus, gene products and pathways found in recent genetic research studies provide hope for development of more effective clinical strategies.
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Meta-analysis of Dense Genecentric Association Studies Reveals Common and Uncommon Variants Associated with Height.
Matthew B Lanktree, Yiran Guo, Muhammed Murtaza, Joseph T Glessner, Swneke D Bailey, N Charlotte Onland-Moret, Guillaume Lettre, Halit Ongen, Ramakrishnan Rajagopalan, Toby Johnson, Haiqing Shen, Christopher P Nelson, Norman Klopp, Jens Baumert, Sandosh Padmanabhan, Nathan Pankratz, James S Pankow, Sonia Shah, Kira Taylor, John Barnard, Bas J Peters, Cliona M Maloney, Maximilian T Lobmeyer, Alice Stanton, M Hadi Zafarmand, Simon P R Romaine, Amar Mehta, Erik P A van Iperen, Yan Gong, Tom S Price, Erin N Smith, Cecilia E Kim, Yun R Li, Folkert W Asselbergs, Larry D Atwood, Kristian M Bailey, Deepak Bhatt, Florianne Bauer, Elijah R Behr, Tushar Bhangale, Jolanda M A Boer, Bernhard O Boehm, Jonathan P Bradfield, Morris Brown, Peter S Braund, Paul R Burton, Cara Carty, Hareesh R Chandrupatla, Wei Chen, John Connell, Chrysoula Dalgeorgou, Anthonius de Boer, Fotios Drenos, Clara C Elbers, James C Fang, Caroline S Fox, Edward C Frackelton, Barry Fuchs, Clement E Furlong, Quince Gibson, Christian Gieger, Anuj Goel, Diederik E Grobbee, Claire Hastie, Philip J Howard, Guan-Hua Huang, W Craig Johnson, Qing Li, Marcus E Kleber, Barbara E K Klein, Ronald Klein, Charles Kooperberg, Bonnie Ky, Andrea LaCroix, Paul Lanken, Mark Lathrop, Mingyao Li, Vanessa Marshall, Olle Melander, Frank D Mentch, Nuala J Meyer, Keri L Monda, Alexandre Montpetit, Gurunathan Murugesan, Karen Nakayama, Dave Nondahl, Abiodun Onipinla, Suzanne Rafelt, Stephen J Newhouse, F George Otieno, Sanjey R Patel, Mary E Putt, Santiago Rodriguez, Radwan N Safa, Douglas B Sawyer, Pamela J Schreiner, Claire Simpson, Suthesh Sivapalaratnam, Sathanur R Srinivasan, Christine Suver, Gary Swergold, Nancy K Sweitzer, Kelly A Thomas, Barbara Thorand, Nicholas J Timpson, Sam Tischfield, Martin Tobin, Maciej Tomaszewski, Maciej Tomaszweski, W M Monique Verschuren, Chris Wallace, Bernhard Winkelmann, Haitao Zhang, Dongling Zheng, Li Zhang, Joseph M Zmuda, Robert Clarke, Anthony J Balmforth, John Danesh, Ian N Day, Nicholas J Schork, Paul I W de Bakker, Christian Delles, David Duggan, Aroon D Hingorani, Joel N Hirschhorn, Marten H Hofker, Steve E Humphries, Mika Kivimäki, Debbie A Lawlor, Kandice Kottke-Marchant, Jessica L Mega, Braxton D Mitchell, David A Morrow, Jutta Palmen, Susan Redline, Denis C Shields, Alan R Shuldiner, Patrick M Sleiman, George Davey Smith, Martin Farrall, Yalda Jamshidi, David C Christiani, Juan P Casas, Alistair S Hall, Pieter A Doevendans, Jason D Christie, Gerald S Berenson, Sarah S Murray, Thomas Illig, Gerald W Dorn, Thomas P Cappola, Eric Boerwinkle, Peter Sever, Daniel J Rader, Muredach P Reilly, Mark Caulfield, Philippa J Talmud, Eric Topol, James C Engert, Kai Wang, Anna Dominiczak, Anders Hamsten, Sean P Curtis, Roy L Silverstein, Leslie A Lange, Marc S Sabatine, Mieke Trip, Danish Saleheen, John F Peden, Karen J Cruickshanks, Winfried März, Jeffrey R O'Connell, Olaf H Klungel, Cisca Wijmenga, Anke Hilse Maitland-van der Zee, Eric E Schadt, Julie A Johnson, Gail P Jarvik, George J Papanicolaou, , Struan F A Grant, Patricia B Munroe, Kari E North, Nilesh J Samani, Wolfgang Koenig, Tom R Gaunt, Sonia S Anand, Yvonne T van der Schouw, Nicole Soranzo, Garret A FitzGerald, Alex Reiner, Robert A Hegele, Hakon Hakonarson, Brendan J Keating.
Am. J. Hum. Genet.
PUBLISHED: 09-14-2010
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Height is a classic complex trait with common variants in a growing list of genes known to contribute to the phenotype. Using a genecentric genotyping array targeted toward cardiovascular-related loci, comprising 49,320 SNPs across approximately 2000 loci, we evaluated the association of common and uncommon SNPs with adult height in 114,223 individuals from 47 studies and six ethnicities. A total of 64 loci contained a SNP associated with height at array-wide significance (p < 2.4 × 10(-6)), with 42 loci surpassing the conventional genome-wide significance threshold (p < 5 × 10(-8)). Common variants with minor allele frequencies greater than 5% were observed to be associated with height in 37 previously reported loci. In individuals of European ancestry, uncommon SNPs in IL11 and SMAD3, which would not be genotyped with the use of standard genome-wide genotyping arrays, were strongly associated with height (p < 3 × 10(-11)). Conditional analysis within associated regions revealed five additional variants associated with height independent of lead SNPs within the locus, suggesting allelic heterogeneity. Although underpowered to replicate findings from individuals of European ancestry, the direction of effect of associated variants was largely consistent in African American, South Asian, and Hispanic populations. Overall, we show that dense coverage of genes for uncommon SNPs, coupled with large-scale meta-analysis, can successfully identify additional variants associated with a common complex trait.
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Increased blood pressure and hyperdynamic cardiovascular responses in carriers of a common hyperfunctional variant of adenylyl cyclase 6.
J. Pharmacol. Exp. Ther.
PUBLISHED: 08-23-2010
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Adenylyl cyclase (ADCY) is a critical regulator of metabolic and cardiovascular function. We have identified a genetic variant (A674S) in ADCY isoform 6 (ADCY6). Subsequent studies demonstrated that the expression of this ADCY6 variant paralleled an increase in adenylyl cyclase-mediated functions. However, the impact of this hyperfunctional variant on cardiovascular function is unknown. Therefore, we evaluated the hemodynamic profile of carriers of ADCY6 A674S. The association of ADCY6 A674S with anthropometric and hemodynamic parameters was assessed in 364 healthy white subjects. The allele encoding this variant was present in 6.9% of the subjects, and those individuals had increased blood pressure. To determine the hemodynamic basis for increased blood pressure in carriers of ADCY6 A674S, we assessed forearm blood flow (FBF) and cardiac output at rest, during handgrip exercise (to test vasodilator responsiveness), and with lower body negative pressure [to test forearm vasoconstrictor and heart rate (HR) responsiveness] in a subsample of 21 subjects. At rest, cardiac output and blood pressure were higher in carriers of ADCY6 A674S. This was paralleled by an increase in plasma renin activity, but not in plasma norepinephrine. During handgrip exercise, FBF and vasodilator responses were greater in carriers of ADCY6 A674S. Responses to reactive hyperemia were not different between genotypes. With lower body negative pressure, the HR response to this orthostatic stress was markedly higher in carriers of ADCY6 A674S. These data indicate that the relatively common hyperfunctional ADCY6 A674S variant underlies a hyperdynamic cardiovascular response and increased blood pressure.
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Mipomersen as a potential adjunctive therapy for hypercholesterolemia.
Expert Opin Pharmacother
PUBLISHED: 08-17-2010
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Mipomersen, an antisense oligonucleotide directed against apolipoprotein B-100 (apoB), was investigated for its safety and efficacy in reducing low-density lipoprotein (LDL) cholesterol (C) as adjunctive treatment for patients with homozygous familial hypercholesterolemia (HoFH) in a Phase III, double-blind, randomized, controlled trial. HoFH patients are very rare in the general population (? 1:1,000,000) and have very high risk for cardiovascular events. HoFH patients respond poorly to statins and most other existing lipid-lowering therapies. Mipomersen (200 or 160 mg) administered subcutaneously to 34 HoFH patients for 26 weeks significantly reduced LDL-C by 24.7% from baseline. In addition, mipomersen lowered plasma lipoprotein (a). In most patients, mipomersen administration was most associated with injection-site reactions; influenza-like symptoms were also more common in mipomersen-treated patients. Four patients had elevated serum alanine aminotransferase (ALT) concentrations, one of whom also had a significant increase in intrahepatic triglyceride content. Another patient met the stopping rules for increased ALT concentrations. No patient developed steatohepatitis during the study. Thus, so far short-term data indicate that mipomersen is safe and effective as an adjunctive drug for lowering LDL-C. Despite these promising results, the longer-term safety and efficacy of mipomersen still needs to be determined.
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Temtamy preaxial brachydactyly syndrome is caused by loss-of-function mutations in chondroitin synthase 1, a potential target of BMP signaling.
Am. J. Hum. Genet.
PUBLISHED: 08-07-2010
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Altered Bone Morphogenetic Protein (BMP) signaling leads to multiple developmental defects, including brachydactyly and deafness. Here we identify chondroitin synthase 1 (CHSY1) as a potential mediator of BMP effects. We show that loss of human CHSY1 function causes autosomal-recessive Temtamy preaxial brachydactyly syndrome (TPBS), mainly characterized by limb malformations, short stature, and hearing loss. After mapping the TPBS locus to chromosome 15q26-qterm, we identified causative mutations in five consanguineous TPBS families. In zebrafish, antisense-mediated chsy1 knockdown causes defects in multiple developmental processes, some of which are likely to also be causative in the etiology of TPBS. In the inner ears of zebrafish larvae, chsy1 is expressed similarly to the BMP inhibitor dan and in a complementary fashion to bmp2b. Furthermore, unrestricted Bmp2b signaling or loss of Dan activity leads to reduced chsy1 expression and, during epithelial morphogenesis, defects similar to those that occur upon Chsy1 inactivation, indicating that Bmp signaling affects inner-ear development by repressing chsy1. In addition, we obtained strikingly similar zebrafish phenotypes after chsy1 overexpression, which might explain why, in humans, brachydactyly can be caused by mutations leading either to loss or to gain of BMP signaling.
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Translating genomic analyses into improved management of coronary artery disease.
Future Cardiol
PUBLISHED: 07-09-2010
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Human genetic variation can modulate pathophysiologic processes that alter susceptibility to complex disease. Recent genomic analyses have sought to identify how common genetic variation alters susceptibility to coronary artery disease (CAD). From genome-wide association studies (GWAS), common genetic variants in several novel chromosomal loci have been associated with CAD. GWAS identified the 9p21 locus as the strongest independent genetic CAD risk factor, along with 11 additional loci that harbor common genetic variants associated with increased CAD risk. A thorough understanding of human genetic variation and genomic analyses will be crucial to understand how GWAS-identified loci increase susceptibility to CAD. This article outlines the relevance of genetic variation in the elucidation of novel CAD risk factors and the clinical utility of genetic variants in the management and treatment of CAD.
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Assessing the association of the HNF1A G319S variant with C-reactive protein in Aboriginal Canadians: a population-based epidemiological study.
Cardiovasc Diabetol
PUBLISHED: 07-06-2010
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C-reactive protein (CRP), a biomarker of inflammation, has been associated with increased risk of developing cardiovascular disease. Common variants of the hepatocyte nuclear factor 1A (HNF1A) gene encoding HNF-1alpha have been associated with plasma CRP in predominantly European Caucasian samples. HNF1A might therefore have an impact on vascular disease and diabetes risk that is mediated by CRP. In an Aboriginal Canadian population, a private polymorphism, HNF1A G319S, was associated with increased prevalence of type 2 diabetes. However, it has not been investigated whether this association is mediated by CRP. We aimed to investigate whether CRP was mediating the association between HNF1A G319S and type 2 diabetes in an Aboriginal Canadian population with a high prevalence of diabetes.
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Genetic variation in hyaluronan metabolism loci is associated with plasma plasminogen activator inhibitor-1 concentration.
Blood
PUBLISHED: 06-17-2010
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Elevated plasma plasminogen activator inhibitor-1 (PAI-1) concentration is associated with cardiovascular disease risk. PAI-1 is the primary inhibitor of fibrinolysis within both the circulation and the arterial wall, playing roles in both atherosclerosis and thrombosis. To define the heritable component, subjects within the population-based SHARE (Study of Health Assessment and Risk in Ethnic groups) and SHARE-AP (Study of Health Assessment and Risk Evaluation in Aboriginal Peoples) studies, composed of Canadians of South Asian (n = 298), Chinese (n = 284), European (n = 227), and Aboriginal (n = 284) descent, were genotyped using the gene-centric Illumina HumanCVD BeadChip. After imputation, more than 150,000 single nucleotide polymorphisms (SNPs) in more than 2000 loci were tested for association with plasma PAI-1 concentration. Marginal association was observed with the PAI-1 locus itself (SERPINE1; P < .05). However, 5 loci (HABP2, HSPA1A, HYAL1, MBTPS1, TARP) were associated with PAI-1 concentration at a P < 1 × 10(-5) threshold. The protein products of 2 of these loci, hyaluronan binding protein 2 (HABP2) and hyaluronoglucosaminidase 1 (HYAL1), play key roles in hyaluronan metabolism, providing genetic evidence to link these pathways.
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Excess of rare variants in genes identified by genome-wide association study of hypertriglyceridemia.
Nat. Genet.
PUBLISHED: 04-01-2010
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Genome-wide association studies (GWAS) have identified multiple loci associated with plasma lipid concentrations. Common variants at these loci together explain <10% of variation in each lipid trait. Rare variants with large individual effects may also contribute to the heritability of lipid traits; however, the extent to which rare variants affect lipid phenotypes remains to be determined. Here we show an accumulation of rare variants, or a mutation skew, in GWAS-identified genes in individuals with hypertriglyceridemia (HTG). Through GWAS, we identified common variants in APOA5, GCKR, LPL and APOB associated with HTG. Resequencing of these genes revealed a significant burden of 154 rare missense or nonsense variants in 438 individuals with HTG, compared to 53 variants in 327 controls (P = 6.2 x 10(-8)), corresponding to a carrier frequency of 28.1% of affected individuals and 15.3% of controls (P = 2.6 x 10(-5)). Considering rare variants in these genes incrementally increased the proportion of genetic variation contributing to HTG.
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Complete Apo AI deficiency in an Iraqi Mandaean family: case studies and review of the literature.
J Clin Lipidol
PUBLISHED: 03-22-2010
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Complete apo A1 deficiency is a rare genetic disorder that has been associated with premature atherosclerosis. We describe a family of Iraqi Mandaean background with complete apo A1 deficiency caused by a new nonsense mutation in the APOA1 gene. Interestingly, there were marked differences in the clinical presentation of the two homozygotes in this family. A 35-year-old woman presented with xanthelasmas and xanthomas but showed only minimal changes on cardiovascular examinations and no clinical symptoms. However, her 37-year-old brother was diagnosed with myocardial infarction at age 35. In addition, both the homozygotes had elevated C-reactive protein levels. The C-reactive protein levels increased three-fold during pregnancy, then decreased postpartum and further decreased with statin treatment. Cholesterol ester transfer protein mass was close to the upper reference range, whereas the activity was low, likely because of the lack of the substrate. Here, we characterize the phenotype and genotype of the first Middle Eastern family with apo A1 deficiency and compare and contrast the findings in the two homozygous siblings and review the previously reported cases of apo A1 deficiency.
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Phenomics: expanding the role of clinical evaluation in genomic studies.
J. Investig. Med.
PUBLISHED: 03-11-2010
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With advances in high-throughput genotyping technologies, the rate-limiting step of large-scale genetic investigations has become the collection of sensitive and specific phenotype information in large samples of study participants. Clinicians play a pivotal role for successful genetic studies because sound clinical acumen can substantially increase study power by reducing measurement error and improving diagnostic precision for translational research. Phenomics is the systematic measurement and analysis of qualitative and quantitative traits, including clinical, biochemical, and imaging methods, for the refinement and characterization of a phenotype. Phenomics requires deep phenotyping, the collection of a wide breadth of phenotypes with fine resolution, and phenomic analysis, composed of constructing heat maps, cluster analysis, text mining, and pathway analysis. In this article, we review the components of phenomics and provide examples of their application to genomic studies, specifically for implicating novel disease processes, reducing sample heterogeneity, hypothesis generation, integration of multiple types of data, and as an extension of Mendelian randomization studies.
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Biological, clinical and population relevance of 95 loci for blood lipids.
Tanya M Teslovich, Kiran Musunuru, Albert V Smith, Andrew C Edmondson, Ioannis M Stylianou, Masahiro Koseki, James P Pirruccello, Samuli Ripatti, Daniel I Chasman, Cristen J Willer, Christopher T Johansen, Sigrid W Fouchier, Aaron Isaacs, Gina M Peloso, Maja Barbalic, Sally L Ricketts, Joshua C Bis, Yurii S Aulchenko, Gudmar Thorleifsson, Mary F Feitosa, John Chambers, Marju Orho-Melander, Olle Melander, Toby Johnson, Xiaohui Li, Xiuqing Guo, Mingyao Li, Yoon Shin Cho, Min Jin Go, Young Jin Kim, Jong-Young Lee, Taesung Park, Kyunga Kim, Xueling Sim, Rick Twee-Hee Ong, Damien C Croteau-Chonka, Leslie A Lange, Joshua D Smith, Kijoung Song, Jing Hua Zhao, Xin Yuan, Jian'an Luan, Claudia Lamina, Andreas Ziegler, Weihua Zhang, Robert Y L Zee, Alan F Wright, Jacqueline C M Witteman, James F Wilson, Gonneke Willemsen, H-Erich Wichmann, John B Whitfield, Dawn M Waterworth, Nicholas J Wareham, Gérard Waeber, Peter Vollenweider, Benjamin F Voight, Veronique Vitart, André G Uitterlinden, Manuela Uda, Jaakko Tuomilehto, John R Thompson, Toshiko Tanaka, Ida Surakka, Heather M Stringham, Tim D Spector, Nicole Soranzo, Johannes H Smit, Juha Sinisalo, Kaisa Silander, Eric J G Sijbrands, Angelo Scuteri, James Scott, David Schlessinger, Serena Sanna, Veikko Salomaa, Juha Saharinen, Chiara Sabatti, Aimo Ruokonen, Igor Rudan, Lynda M Rose, Robert Roberts, Mark Rieder, Bruce M Psaty, Peter P Pramstaller, Irene Pichler, Markus Perola, Brenda W J H Penninx, Nancy L Pedersen, Cristian Pattaro, Alex N Parker, Guillaume Paré, Ben A Oostra, Christopher J O'Donnell, Markku S Nieminen, Deborah A Nickerson, Grant W Montgomery, Thomas Meitinger, Ruth McPherson, Mark I McCarthy, Wendy McArdle, David Masson, Nicholas G Martin, Fabio Marroni, Massimo Mangino, Patrik K E Magnusson, Gavin Lucas, Robert Luben, Ruth J F Loos, Marja-Liisa Lokki, Guillaume Lettre, Claudia Langenberg, Lenore J Launer, Edward G Lakatta, Reijo Laaksonen, Kirsten O Kyvik, Florian Kronenberg, Inke R König, Kay-Tee Khaw, Jaakko Kaprio, Lee M Kaplan, Asa Johansson, Marjo-Riitta Järvelin, A Cecile J W Janssens, Erik Ingelsson, Wilmar Igl, G Kees Hovingh, Jouke-Jan Hottenga, Albert Hofman, Andrew A Hicks, Christian Hengstenberg, Iris M Heid, Caroline Hayward, Aki S Havulinna, Nicholas D Hastie, Tamara B Harris, Talin Haritunians, Alistair S Hall, Ulf Gyllensten, Candace Guiducci, Leif C Groop, Elena González, Christian Gieger, Nelson B Freimer, Luigi Ferrucci, Jeanette Erdmann, Paul Elliott, Kenechi G Ejebe, Angela Döring, Anna F Dominiczak, Serkalem Demissie, Panagiotis Deloukas, Eco J C de Geus, Ulf de Faire, Gabriel Crawford, Francis S Collins, Yii-Der I Chen, Mark J Caulfield, Harry Campbell, Noel P Burtt, Lori L Bonnycastle, Dorret I Boomsma, S Matthijs Boekholdt, Richard N Bergman, Inês Barroso, Stefania Bandinelli, Christie M Ballantyne, Themistocles L Assimes, Thomas Quertermous, David Altshuler, Mark Seielstad, Tien Y Wong, E-Shyong Tai, Alan B Feranil, Christopher W Kuzawa, Linda S Adair, Herman A Taylor, Ingrid B Borecki, Stacey B Gabriel, James G Wilson, Hilma Holm, Unnur Thorsteinsdottir, Vilmundur Gudnason, Ronald M Krauss, Karen L Mohlke, José M Ordovás, Patricia B Munroe, Jaspal S Kooner, Alan R Tall, Robert A Hegele, John J P Kastelein, Eric E Schadt, Jerome I Rotter, Eric Boerwinkle, David P Strachan, Vincent Mooser, Kari Stefansson, Muredach P Reilly, Nilesh J Samani, Heribert Schunkert, L Adrienne Cupples, Manjinder S Sandhu, Paul M Ridker, Daniel J Rader, Cornelia M van Duijn, Leena Peltonen, Gonçalo R Abecasis, Michael Boehnke, Sekar Kathiresan.
Nature
PUBLISHED: 02-25-2010
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Plasma concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides are among the most important risk factors for coronary artery disease (CAD) and are targets for therapeutic intervention. We screened the genome for common variants associated with plasma lipids in >100,000 individuals of European ancestry. Here we report 95 significantly associated loci (P < 5 x 10(-8)), with 59 showing genome-wide significant association with lipid traits for the first time. The newly reported associations include single nucleotide polymorphisms (SNPs) near known lipid regulators (for example, CYP7A1, NPC1L1 and SCARB1) as well as in scores of loci not previously implicated in lipoprotein metabolism. The 95 loci contribute not only to normal variation in lipid traits but also to extreme lipid phenotypes and have an impact on lipid traits in three non-European populations (East Asians, South Asians and African Americans). Our results identify several novel loci associated with plasma lipids that are also associated with CAD. Finally, we validated three of the novel genes-GALNT2, PPP1R3B and TTC39B-with experiments in mouse models. Taken together, our findings provide the foundation to develop a broader biological understanding of lipoprotein metabolism and to identify new therapeutic opportunities for the prevention of CAD.
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Rare ATGL haplotypes are associated with increased plasma triglyceride concentrations in the Greenland Inuit.
Int J Circumpolar Health
PUBLISHED: 02-20-2010
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To genotype common genetic variants found in the adipose triglyceride lipase (ATGL) gene and test them for association with cardiovascular disease risk factors in the Greenland Inuit.
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Advances in genomic analysis of stroke: what have we learned and where are we headed?
Stroke
PUBLISHED: 02-18-2010
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As a result of technological advances, the genomic analysis of stroke has shifted from candidate gene association studies to genome-wide association studies (GWAS). Agnostic GWAS evaluate up to 90% of common genetic variation in a single experiment, creating an improved framework for identifying novel genetic leads for biochemical and cellular mechanisms underlying stroke. Given the ubiquity of the GWAS approach, it has become essential for stroke researchers and clinicians to be able to interpret GWAS results. Thus, we review the basic elements of design, methods, presentation, and interpretation of GWAS in the context of stroke research. In 8 recent stroke GWAS reports, no single locus has been identified in 2 GWAS at a genome-wide level of significance. Additionally, no significant association signal between stroke and a locus with previous evidence from candidate gene studies of stroke has been identified yet. Some caveats of the approach and future directions for stroke genomics are discussed, including the use of intermediate phenotypes, Mendelian randomization, phenomics, and deep resequencing. Intelligent, appropriately powered, multidisciplinary studies incorporating knowledge from clinical medicine, epidemiology, genetics, and molecular biology will be required to fully characterize the genomic contributors to stroke.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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