Current prenatal diagnosis for fetal aneuploidies (including trisomy 21 [T21]) generally relies on an initial biochemical serum-based noninvasive prenatal testing (NIPT) after which women who are deemed to be at high risk are offered an invasive confirmatory test (amniocentesis or chorionic villi sampling for a fetal karyotype), which is associated with a risk of fetal miscarriage. Recently, genomics-based NIPT (gNIPT) was proposed for the analysis of fetal genomic DNA circulating in maternal blood. The diffusion of this technology in routine prenatal care could be a major breakthrough in prenatal diagnosis, since initial research studies suggest that this novel approach could be very effective and could reduce substantially the number of invasive procedures. However, the limitations of gNIPT may be underappreciated. In this review, we examine currently published literature on gNIPT to highlight advantages and limitations. At this time, the performance of gNIPT is relatively well-documented only in high-risk pregnancies for T21 and trisomy 18. This additional screening test may be an option for women classified as high-risk of aneuploidy who wish to avoid invasive diagnostic tests, but it is crucial that providers carefully counsel patients about the test's advantages and limitations. The gNIPT is currently not recommended as a first-tier prenatal screening test for T21. Since gNIPT is not considered as a diagnostic test, a positive gNIPT result should always be confirmed by an invasive test, such as amniocentesis or chorionic villus sampling. Validation studies are needed to optimally introduce this technology into the existing routine workflow of prenatal care.
We report a new and rare case of recurrent anencephaly in a family with no other apparent abnormalities. The karyotypes of the family and all affected subjects were normal. Thorough mutational analyses of VANGL1 of chromosome 1p13.1 and FOXN1 of chromosome 17q11-q12, genes that are associated with phenotypes of the anencephaly spectrum, unfortunately did not disclose any DNA variations in an affected fetus of this family. The etiology of recurrent anencephaly in this family is therefore due to mutations in genes yet to be discovered, perhaps of the planar cell polarity pathway, or to possible environmental gestational factors during development.
We examined the association between midtrimester intra-amniotic sludge and spontaneous preterm birth (PTB) in asymptomatic women undergoing amniocentesis. We performed a prospective cohort study of women having an amniocentesis for fetal karyotyping between 14 and 24 weeks gestation. Cervical length and the presence of amniotic sludge were assessed by transvaginal ultrasound. Amniotic fluid concentrations of matrix metalloproteinase-8, glucose and lactate were measured. Early (<32 weeks) and late (32 to 36 weeks) preterm premature rupture of membranes (PPROM) and spontaneous PTB constituted primary outcomes. Nonparametric analyses were conducted. Three hundred ten women, including 94 (30%) with free-floating echogenic particles and 16 (5%) with dense amniotic sludge, were recruited. Dense amniotic sludge was linked with early (13%) but not with late (0%) primary outcome ( P?0.01). Two women with combined dense amniotic sludge and short cervix delivered 4 and 10 weeks later (at 20 and 25 weeks, respectively) and had a higher median amniotic lactate concentration than controls ( P?0.05). A third woman with dense amniotic sludge at 15 weeks was diagnosed with a short cervix and an intra-amniotic infection at 22 weeks that was eradicated with intravenous antibiotics. Midtrimester dense amniotic sludge is associated with early PPROM and spontaneous PTB.
Array comparative genomic hybridisation (aCGH) represents a major advance in the ability to detect chromosomal imbalances (CI). A recent meta-analysis recommended aCGH for replacing karyotyping for patients with unexplained disabilities. However, favouring aCGH over karyotyping must be based on solid evidence due to the major implications of selecting a preferential diagnostic tool.
This is an 11-year survey of molecular analysis of APC germline mutations for the province of Quebec done at the Molecular Pathology Unit of the Jewish General Hospital which offers genetic testing for hereditary forms of colorectal cancer for the whole of Quebec province. We report on 47 unique mutations seen in 66 families affected with familial adenomatous polyposis. Of these unique mutations, 60% are short indels, 28% are point mutations, and 6% are whole exon deletions. The absence of founder mutations and the variety of mutations encountered reinforce the value of RNA-based testing and the need for gene dosage techniques such as multiplex ligation-dependent probe amplification.
In all, 80% of antenatal karyotypes are generated by Downs syndrome screening programmes (DSSP). After a positive screening, women are offered prenatal foetus karyotyping, the gold standard. Reliable molecular methods for rapid aneuploidy diagnosis (RAD: fluorescence in situ hybridization (FISH) and quantitative fluorescence PCR (QF-PCR)) can detect common aneuploidies, and are faster and less expensive than karyotyping.In the UK, RAD is recommended as a standalone approach in DSSP, whereas the US guidelines recommend that RAD be followed up by karyotyping. A cost-effectiveness (CE) analysis of RAD in various DSSP is lacking. There is a debate over the significance of chromosome abnormalities (CA) detected with karyotyping but not using RAD. Our objectives were to compare the CE of RAD versus karyotyping, to evaluate the clinically significant missed CA and to determine the impact of detecting the missed CA. We performed computer simulations to compare six screening options followed by FISH, PCR or karyotyping using a population of 110948 pregnancies. Among the safer screening strategies, the most cost-effective strategy was contingent screening with QF-PCR (CE ratio of $24084 per Downs syndrome (DS) detected). Using karyotyping, the CE ratio increased to $27898. QF-PCR missed only six clinically significant CA of which only one was expected to confer a high risk of an abnormal outcome. The incremental CE ratio (ICER) to find the CA missed by RAD was $66608 per CA. These costs are much higher than those involved for detecting DS cases. As the DSSP are mainly designed for DS detection, it may be relevant to question the additional costs of karyotyping.
Otocephaly is a severe and lethal malformation. We report a new case of a fetus with agnathia-otocephaly, presenting only the facial findings but with otherwise normal organs. The fetal karyotype was normal. We examined the fetal DNA for uniparental disomy of chromosomes 3 and 4, since the mother is a carrier of a t(3;4) chromosome, but did not identify any evidence. We were also unable to find mutations or possible associations with candidate otocephalic genes, including OTX2 and PGAP1. These findings suggest that the molecular etiology of agnathia-otocephaly is still unknown with a mutation yet to be identified in humans.
Agnathia-otocephaly, a rare, sporadic and lethal malformation, is characterized by microstomia (small mouth), aglossia (absence of the tongue), agnathia (absence of the lower jaw) and abnormally positioned ears. It is a principal anomaly derived from the first pharyngeal arch as a consequence of failed mesenchymal migration of the maxillary prominence and atrophy in the development of the mandibular prominences. Unfortunately, these patients have poor prognoses and may succumb to death shortly after birth due to respiratory problems if appropriate airway management is not implemented. Difficulties persist in the prenatal diagnosis of agnathia-otocephalic patients. However, two- and three-dimensional ultrasonography, computed tomography and magnetic resonance imaging technologies now offer significant improvements in refining the resolution of distinctive facial anomalies. This complex disorder can be attributed to both genetic and teratogenic causes, in addition to other unidentifiable factors. Furthermore, studies in model organisms, in particular mice, have unraveled potential genetic pathways that may contribute to the etiology. This article highlights current perspectives on agnathia-otocephaly with a focus on the etiological causes and issues concerning prenatal diagnosis, differential diagnosis, prognosis and genetic counseling. Finally, studies using animal models especially genetically engineered mice are described to comprehend the molecular genetic interactions that may occur during the genesis of this intriguing craniofacial birth defect.
Cellular cardiomyoplasty is undergoing intensive investigation as a new form of therapy for severely damaged hearts. Among several cell types, mesenchymal stem cells (MSCs) have been proposed as a potential cell source. MSC can be found in adult tissues or in fetal tissues like the umbilical chord blood, amniotic membrane, or amniotic fluid (AF). AF-MSCs have properties intermediate between embryonic and adult MSC, which make them particularly attractive for cellular regeneration. It has been shown that MSC could differentiate in cardiomyocytes-like cells in vitro. In some animal models, it has also been shown that transplanted MSC could engraft and show some cardiomyocytes-like characteristics. Since MSC do not express HLA-DR and present in vitro and in vivo immunosuppressive properties, they can be envisioned to be used in allogenic cellular cardiomyoplasty. Based on these promises, MSC from adult donors are currently used in small safety and feasibility trials. No clinical trial using AF-MSC has been performed yet. Still, the exact role of true cell repopulation and in situ cardiomyocytes differentiation versus pure paracrine effect after cell transplantation is currently much debated. Cellular cardiomyoplasty is a fascinating new area of investigation in regenerative medicine. Although considerable knowledge has been gained over the last decade on the use of MSC as a potential stem cell (SC) source, many issues remain unsolved. Because of several limitations in animal models, clinical studies in highly selected patients balancing the risks and benefits are required. In that regard, MSCs obtained from the fetal AF are a potential new source of SCs that need to be further investigated for cellular cardiomyoplasty.
To assess and compare the cost effectiveness of three different strategies for prenatal screening for Downs syndrome (integrated test, sequential screening, and contingent screenings) and to determine the most useful cut-off values for risk.
holoprosencephaly is the most common forebrain malformation syndrome with a multifactorial etiology. Currently, mutations are identified in 5-10% of non syndromic, non-chromosomal cases in at least 12 genes. We report the molecular prenatal diagnosis of a fetus with alobar holoprosencephaly.
Human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) have an endless self-renewal capacity and can theoretically differentiate into all types of lineages. They thus represent an unlimited source of cells for therapies of regenerative diseases, such as Duchenne muscular dystrophy (DMD), and for tissue repair in specific medical fields. However, at the moment, the low number of efficient specific lineage differentiation protocols compromises their use in regenerative medicine. We developed a two-step procedure to differentiate hESCs and dystrophic hiPSCs in myogenic cells. The first step was a culture in a myogenic medium and the second step an infection with an adenovirus expressing the myogenic master gene MyoD. Following infection, the cells expressed several myogenic markers and formed abundant multinucleated myotubes in vitro. When transplanted in the muscle of Rag/mdx mice, these cells participated in muscle regeneration by fusing very well with existing muscle fibers. Our findings provide an effective method that will permit to use hESCs or hiPSCs for preclinical studies in muscle repair.
We report a new case of a fetus with holoprosencephaly-polydactyly syndrome, also known as pseudo-trisomy 13 syndrome, and no other apparent abnormalities except for septal agenesis of the left lung. The fetal karyotype was normal. Mutational analysis of five genes (SHH, SIX3, TGIF, ZIC2, and GLI3), which are major genes associated with holoprosencephaly, did not disclose any mutational findings. We therefore propose that the abnormalities of our fetus support the demarcation of this syndrome as an autonomous phenotype. Specific diagnostic criteria for holoprosencephaly-polydactyly syndrome need to be complemented by the absence of mutations in the major holoprosencephaly genes.
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