In the elderly, degenerative changes in the lumbar spine are common, contributing to falsely elevated bone mineral density (BMD) values. The parathyroid hormone (PTH) system plays an important role in the regulation of bone turnover and we explore the hypothesis that polymorphisms (SNPs) within genes in this pathway (PTH, PTHLH, PTH1R and PTH2R) contribute to degenerative manifestations of the spine in elderly women. The study included 1,004 Swedish women aged 75 years from the population-based OPRA cohort who attended follow-up at 5 and 10 years. Lumbar spine BMD was assessed by dual energy X-ray absorptiometry (DXA) and each individual vertebra was evaluated visually on the DXA image for apparent degenerative manifestations. Six SNPs in PTH and 3 SNPs each in PTH1R, PTH2R and PTHLH were analysed. Among women with degenerative manifestations at the lumbar spine, there was an over-representation at baseline of those carrying the PTH2R SNP rs897083 A-allele (p = 0.0021; odds ratio 1.5 95 % CI 1.2-2.0) and across the duration of follow-up (p = 0.0008). No association was observed between degenerative manifestations and variation in the other genes. None of the PTH hormone system genes were associated with vertebral fracture. Variation in the PTH2R gene (Chr2q34, rs897083) may contribute to the age-associated degenerative manifestations that develop at the lumbar spine.
BackgroundIn experimental studies, the apolipoprotein D (APOD) and the sigma receptor type 1 (SIGMAR1) have been related to processes of brain damage, repair and plasticity.MethodsWe examined blood samples from 3081 ischemic stroke (IS) patients and 1595 control subjects regarding 10 single nucleotide polymorphisms (SNPs) in the APOD (chromosomal location 3q29) and SIGMAR1 (chromosomal location 9p13) genes to find possible associations with IS risk, IS severity (NIHSS-score) and recovery after IS (modified Rankin Scale at 90 days). Simple/multiple logistic regression and Spearman¿s rho were utilized for the analyses.ResultsAmong the SNPs analyzed, rs7659 within the APOD gene showed a possible association with stroke risk (OR¿=¿1.12; 95% CI: 1.01-1.25; P¿=¿0.029) and stroke severity (NIHSS¿¿¿16) (OR¿=¿0.70; 95% CI: 0.54-0.92; P¿=¿0.009) when controlling for age, sex and vascular risk factors for stroke. No SNP showed an association with stroke recovery (mRS).ConclusionsWe conclude that the SNP rs7659 within the APOD gene might be related to risk and severity of ischemic stroke in patients.
Osteoporosis is characterized by reduced bone mineral density (BMD) and increased fracture risk. Fat mass is a determinant of bone strength and both phenotypes have a strong genetic component. In this study, we examined the association between obesity associated polymorphisms (SNPs) with body composition, BMD, Ultrasound (QUS), fracture and biomarkers (Homocysteine (Hcy), folate, Vitamin D and Vitamin B12) for obesity and osteoporosis. Five common variants: rs17782313 and rs1770633 (melanocortin 4 receptor (MC4R); rs7566605 (insulin induced gene 2 (INSIG2); rs9939609 and rs1121980 (fat mass and obesity associated (FTO) were genotyped in 2 cohorts of Swedish women: PEAK-25 (age 25, n?=?1061) and OPRA (age 75, n?=?1044). Body mass index (BMI), total body fat and lean mass were strongly positively correlated with QUS and BMD in both cohorts (r(2)?=?0.2-0.6). MC4R rs17782313 was associated with QUS in the OPRA cohort and individuals with the minor C-allele had higher values compared to T-allele homozygotes (TT vs. CT vs.
Infantile hypertrophic pyloric stenosis (IHPS) is a common cause of upper gastrointestinal obstruction during infancy. A multifactorial background of the disease is well established. Multiple susceptibility loci including the neuronal nitric oxide synthase (NOS1) gene have previously been linked to IHPS, but contradictory results of linkage studies in different materials indicate genetic heterogeneity. To identify IHPS susceptibility loci, we conducted a genome-wide linkage analysis in 37 Swedish families. In regions where the Swedish material showed most evidence in favor of linkage, 31 additional British IHPS families were analyzed. Evidence in favor of significant linkage was observed in the Swedish material to two loci on chromosome 2q24 (non-parametric linkage (NPL) =3.77) and 7p21 (NPL=4.55). In addition, evidence of suggestive linkage was found to two loci on chromosome 6p21 (NPL=2.97) and 12q24 (NPL=2.63). Extending the material with British samples did not enhance the level of significance. Regions with linkage harbor interesting candidate genes, such as glucagon-like peptide-2 (GLP-2 encoded by the glucagon gene GCG), NOS1, motilin (MLN) and neuropeptide Y (NPY). The coding exons for GLP-2, and NPY were screened for mutations with negative results. In conclusion, we could confirm suggestive linkage to the region harboring the NOS1 gene and detected additional novel susceptibility loci for IHPS.
Susceptibility to osteoporotic fracture is influenced by genetic factors that can be dissected by whole-genome linkage analysis in experimental animal crosses. The aim of this study was to characterize quantitative trait loci (QTLs) for biomechanical and two-dimensional dual-energy X-ray absorptiometry (DXA) phenotypes in reciprocal F2 crosses between diabetic GK and normo-glycemic F344 rat strains and to identify possible co-localization with previously reported QTLs for bone size and structure. The biomechanical measurements of rat tibia included ultimate force, stiffness and work to failure while DXA was used to characterize tibial area, bone mineral content (BMC) and areal bone mineral density (aBMD). F2 progeny (108 males, 98 females) were genotyped with 192 genome-wide markers followed by sex- and reciprocal cross-separated whole-genome QTL analyses. Significant QTLs were identified on chromosome 8 (tibial area; logarithm of odds (LOD)?=?4.7 and BMC; LOD?=?4.1) in males and on chromosome 1 (stiffness; LOD?=?5.5) in females. No QTLs showed significant sex-specific interactions. In contrast, significant cross-specific interactions were identified on chromosome 2 (aBMD; LOD?=?4.7) and chromosome 6 (BMC; LOD?=?4.8) for males carrying F344mtDNA, and on chromosome 15 (ultimate force; LOD?=?3.9) for males carrying GKmtDNA, confirming the effect of reciprocal cross on osteoporosis-related phenotypes. By combining identified QTLs for biomechanical-, size- and qualitative phenotypes (pQCT and 3D CT) from the same population, overlapping regions were detected on chromosomes 1, 3, 4, 6, 8 and 10. These are strong candidate regions in the search for genetic risk factors for osteoporosis.
Type 2 diabetes (T2D) evolves when insulin secretion fails. Insulin release from the pancreatic ? cell is controlled by mitochondrial metabolism, which translates fluctuations in blood glucose into metabolic coupling signals. We identified a common variant (rs950994) in the human transcription factor B1 mitochondrial (TFB1M) gene associated with reduced insulin secretion, elevated postprandial glucose levels, and future risk of T2D. Because islet TFB1M mRNA levels were lower in carriers of the risk allele and correlated with insulin secretion, we examined mice heterozygous for Tfb1m deficiency. These mice displayed lower expression of TFB1M in islets and impaired mitochondrial function and released less insulin in response to glucose in vivo and in vitro. Reducing TFB1M mRNA and protein in clonal ? cells by RNA interference impaired complexes of the mitochondrial oxidative phosphorylation system. Consequently, nutrient-stimulated ATP generation was reduced, leading to perturbed insulin secretion. We conclude that a deficiency in TFB1M and impaired mitochondrial function contribute to the pathogenesis of T2D.
The F344 rat carries alleles contributing to bone fragility while the GK rat spontaneously develops type-2 diabetes. These characteristics make F344×GK crosses well suited for the identification of genes related to bone size and allow for future investigation on the association with type-2 diabetes. The aim of this study was to identify quantitative trait loci (QTLs) for bone size phenotypes measured by a new application of three-dimensional computed tomography (3DCT) and to investigate the effects of sex- and reciprocal cross. Tibia from male and female GK and F344 rats, representing the parental, F1 and F2 generations, were examined with 3DCT and analyzed for: total and cortical volumetric BMD, straight and curved length, peri- and endosteal area at mid-shaft. F2 progeny (108 male and 98 female) were genotyped with 192 genome-wide microsatellite markers (average distance 10 cM). Sex- and reciprocal cross-separated QTL analyses were performed for the identification of QTLs linked to 3DCT phenotypes and true interactions were confirmed by likelihood ratio analysis in all F2 animals. Several genome-wide significant QTLs were found in the sex- and reciprocal cross-separated progeny on chromosomes (chr) 1, 3, 4, 9, 10, 14, and 17. Overlapping QTLs for both males and females in the (GK×F344)F2 progeny were located on chr 1 (39-67 cM). This region confirms previously reported pQCT QTLs and overlaps loci for fasting glucose. Sex separated linkage analysis confirmed a male specific QTL on chr 9 (67-82 cM) for endosteal area at the fibula site. Analyses separating the F2 population both by sex and reciprocal cross identified cross specific QTLs on chr 14 (males) and chr 3 and 4 (females). Two loci, chr 4 and 6, are unique to 3DCT and separate from pQCT generated loci. The 3DCT method was highly reproducible and provided high precision measurements of bone size in the rat enabling identification of new sex- and cross-specific loci. The QTLs on chr 1 indicate potential genetic association between bone-related phenotypes and traits affecting type-2 diabetes. The results illustrate the complexity of the genetic architecture of bone size phenotypes and demonstrate the importance of complementary methods for bone analysis.
Several common genetic variations have been associated with type 2 diabetes, but the exact disease mechanisms are still poorly elucidated. Using congenic strains from the diabetic Goto-Kakizaki rat, we identified a 1.4-megabase genomic locus that was linked to impaired insulin granule docking at the plasma membrane and reduced beta cell exocytosis. In this locus, Adra2a, encoding the alpha2A-adrenergic receptor [alpha(2A)AR], was significantly overexpressed. Alpha(2A)AR mediates adrenergic suppression of insulin secretion. Pharmacological receptor antagonism, silencing of receptor expression, or blockade of downstream effectors rescued insulin secretion in congenic islets. Furthermore, we identified a single-nucleotide polymorphism in the human ADRA2A gene for which risk allele carriers exhibited overexpression of alpha(2A)AR, reduced insulin secretion, and increased type 2 diabetes risk. Human pancreatic islets from risk allele carriers exhibited reduced granule docking and secreted less insulin in response to glucose; both effects were counteracted by pharmacological alpha(2A)AR antagonists.
A genome-wide linkage analysis to identify quantitative trait loci (QTLs) for bone phenotypes was performed in an F(2) intercross of inbred spontaneously type 2 diabetic GK and normoglycemic F344 rats (108 males and 98 females). The aim of the study was to locate genome regions with candidate genes affecting trabecular and cortical bone and to investigate the effects of sex and reciprocal cross. pQCT was used to determine tibial bone phenotypes in the F(2) rats, comprising reciprocal crosses with divergent mitochondrial (mt) DNA. Sex and reciprocal cross-separated QTL analyses were performed followed by assessment of specific interactions. Four genome-wide significant QTLs linked to either cortical vBMD, tibia length, body length, or metaphyseal area were identified in males on chromosomes (chr) 1, 8, and 15. In females, three significant QTLs linked to cortical BMC or metaphyseal total vBMD were identified on chr 1 and 2. Several additional suggestive loci for trabecular and cortical traits were detected in both males and females. Four female-specific QTLs on chr 2, 3, 5, and 10 and four reciprocal cross-specific QTLs on chr 1, 10, and 18 were identified, suggesting that both sex and mt genotype influence the expression of bone phenotypes.
The proper function of mammalian mitochondria necessitates a coordinated expression of both nuclear and mitochondrial genes, most likely due to the co-evolution of nuclear and mitochondrial genomes. The non-protein coding regions of mitochondrial DNA (mtDNA) including the D-loop, tRNA and rRNA genes form a major component of this regulated expression unit. Here we present comparative analyses of the non-protein-coding regions from 27 Rattus norvegicus mtDNA sequences. There were two variable positions in 12S rRNA, 20 in 16S rRNA, eight within the tRNA genes and 13 in the D-loop. Only one of the three neutrality tests used demonstrated statistically significant evidence for selection in 16S rRNA and tRNA-Cys. Based on our analyses of conserved sequences, we propose that some of the variable nucleotide positions identified in 16S rRNA and tRNA-Cys, and the D-loop might be important for mitochondrial function and its regulation.
We have previously performed a genome-wide linkage study in Scandinavian Type 1 diabetes (T1D) families. In the Swedish families, we detected suggestive linkage (LOD?2.2) to the chromosome 5p13-q13 region. The aim of our study was to investigate the linked region in search for possible T1D susceptibility genes.
Previous reports have shown ambiguous findings regarding the possible associations between ischaemic stroke (IS) and single nucleotide polymorphisms (SNPs) in the phosphodiesterase 4D (PDE4D) gene region. The SNP rs12188950 (or SNP45) has often been studied in this context. We performed a multi-centre study involving a large sample of 2599 IS patients and 2093 control subjects from the south and west regions of Sweden to replicate previous studies regarding IS risk and rs12188950. Subjects from Lund Stroke Register (LSR), Malmö Diet and Cancer Study (MDC) and Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS) were enroled. Subgroups of participants with hypertension and participants <55 years of age, as well as the TOAST subgroups large vessel disease, small vessel disease and cardioembolism, were also assessed. Univariate odds ratios (ORs) and ORs controlling for hypertension, diabetes and current smoking were calculated. We additionally performed a meta-analysis including 10,500 patients and 10,102 control subjects from 17 publications (including the present study). When assessing pooled data from LSR, MDC and SAHLSIS we obtained no association between IS and rs12188950 for all participants (OR=0.93; 95% confidence interval (CI): 0.83-1.05). Significant associations were not found for hypertensive participants or participants with age <55, or when separately evaluating patients from the three different TOAST subgroups. The meta-analysis showed no significant overall estimate (OR=0.96; 95% CI: 0.89-1.04) with significant heterogeneity for random effect (P=0.042). No effect from rs12188950 on IS was found from either our pooled multi-centre data or the performed meta-analysis. We did not find any association between the examined subgroups and rs12188950 either.
We developed an inbred rat model of diabetic embryopathy, in which the offspring displays skeletal malformations (agnathia or micrognathia) when the mother is diabetic, and no malformations when she is not diabetic. Our aim was to find genes controlling the embryonic maldevelopment in a diabetic environment. We contrasted the fetal outcome in inbred Sprague-Dawley L rats (20% skeletal malformations in diabetic pregnancy) with that of inbred Wistar Furth rats (denotedW, no skeletal malformations in diabetic pregnancy). We used offspring from the backcross F(1)×L to probe for the genetic basis for malformation of the mandible in diabetic pregnancy. A set of 186 fetuses (93 affected, 93 unaffected) was subjected to a whole genome scan with 160 micro satellites. Analysis of genotype distribution indicated 7 loci on chromosome 4, 10 (3 loci), 14, 18, and 19 in the teratogenic process (and 14 other loci on 12 chromosomes with less strong association to the malformations), several of which contained genes implicated in other experimental studies of diabetic embryopathy. These candidate genes will be scrutinized in further experimentation. We conclude that the genetic involvement in rodent diabetic embryopathy is polygenic and predisposing for congenital malformations.
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