Value of Nuchal Translucency in Detection of Chromosomal Aberration in Vietnam Population

Objective: To examine the sensitivity and specificity of different thresholds of nuchal translucency in diagnosis of chromosomal defects. Study Design: This is a longitudinal study of pregnant women have first trimester screening and ultrasound in center of diagnostic antenatal of national hospital of obstetrics and gynecology. A follow-up was made to identify, in all singleton pregnancies in both group of which fetal karyotyping was made and group of normal fetuses. The threshold for nuchal translucency was divided in to above the 95th percentile, the 99th percentile, the 3.0mm and 2.5 MoM of nuchal translucency. The sensitivity and specificity ware calculated in order to diagnosis the chromosomal abbreviation. Results: The research identified 2645 fetuses, 743 amniocentesis (28%). There is 32.4% fetus has NT ≥ the 95th percentile, 28.6% ≥ 2.5mm percentile, 22.3% ≥ 3.0mm, 16.6% above 2.5 MoM. The fetal karyotype was abnormal in 157 (5.8%) pregnancies. The popular conditions were found including trisomy 21(52.2%). Then structural rearrangements occupied 31.2%. Other chromosomes like 13,18,21 occupied 12.7%. The abnormal of sex chromosome was smallest proportion with only 3.8%. At the 95th percentile of nuchal translucency has the highest sensitivity in detection of chromosomal defects (99.4%) but the threshold 2.5mm has a better detection rate (20.4%). The cut off 3.0mm has a better positive prediction rate (22.3%) but could detect less defects (only 132/157 abbreviation). The threshold 2.5xMoM had the highest specificity (86.4%) but lowest sensitivity (only 65%). Conclusion: In fetuses with increased nuchal translucency, more than a half of the chromosomally abnormal group is affected by defects other than trisomy 21 (52.2%). Using threshold 2.5mm helps detect more 23 chromosomal defects in comparison with the threshold 3.0mm and it had the highest average of sensitivity and specificity (87.25%).

Diagnostic value of systematic ultrasonography for trisomy 18 syndrome in fetuses before 16 weeks gestation

Purpose To explore the diagnostic value of systematic fetal ultrasonography for trisomy 18 (T18) syndrome before 16 weeks gestation. Methods A total of 12 fetuses with T18 were selected as research subjects and their nuchal translucency (NT) screening and fetal systematic ultrasonographic images acquired at 11–15 weeks were retrospectively analyzed. Results In the 12 fetuses’ NT screening, ten fetuses showed NT thickening, one showed nuchal cystic hygroma, four showed reversed a-wave ductus venosus flow, and three showed omphalocele. The most common anomalies on the systematic ultrasonography before 16 weeks gestation were cardiac defects (12/12, 100%), omphalocele (4/12, 33.3%), limb anomalies (5/12, 41.7%), and facial anomalies (3/12, 25.0%). Seven of the 12 fetuses had multiple structural malformations: three had two structural malformations (25.0%), three had three structural malformations (25.0%), and one had four structural malformations (8.3%). Conclusion Systematic fetal ultrasonography before 16 weeks gestation can detect most of the structural malformations of T18, effectively shortening the prenatal diagnosis time. It is therefore of great importance for reducing the birth rate of children with T18 and minimizing the physical and mental damage to mothers and their families.

Genetic and imaging study of a case with multiple malformations: limb body wall complex

The Limb-Wall Complex is a rare and sporadic congenital anomaly characterized by multiple craniofacial and thoracoabdominal malformations as well as involvement of the spine and lower extremities. The etiology is unknown and the chromosomal study is normal, however, it is related to an alteration in the formation of the umbilical cord (short umbilical cord), abdominal placental insertion and persistence of the extraembryonic coelom. This condition causes intracavitary organs to be exposed and adhered to the placenta and consequently also attached to the mother’s uterus. The diagnosis can be made from the first trimester of gestation with a nuchal translucency ultrasound in order to detect this pathology in time and to be able to offer good genetic counseling to the parents, since the prognosis is not favorable

Biallelic ANGPT2 loss-of-function causes severe early-onset non-immune hydrops fetalis

BackgroundHydrops fetalis, a pathological fluid accumulation in two or more body compartments, is aetiologically heterogeneous. We investigated a consanguineous family with recurrent pregnancy loss due to severe early-onset non-immune hydrops fetalis.Methods and resultsWhole exome sequencing in four fetuses with hydrops fetalis revealed that they were homozygous for the angiopoietin-2 (ANGPT2) variant Chr8 (GRCh37/Hg19): 6385085T>C, NM_001147.2:c.557A>G. The substitution introduces a cryptic, exonic splice site predicted to result in loss of 10 nucleotides with subsequent shift in reading frame, leading to a premature stop codon. RNA analysis in the heterozygous parents demonstrated loss of detectable mutant allele, indicative of loss-of-function via nonsense-mediated mRNA decay. Serum ANGPT2 levels were reduced in the parents. In a pregnancy with a healthy, heterozygous child, transiently increased fetal nuchal translucency was noted.ConclusionPathogenic heterozygous ANGPT2 missense variants were recently shown to cause autosomal dominant primary lymphoedema. ANGPT2 is a ligand of the TIE1-TIE2 (tyrosine kinase with immunoglobulin-like and epidermal growth factor-like domains 1 and 2) pathway. It is critical to the formation and remodelling of blood and lymphatic vessels and is involved in vessel maintenance. ANGPT2 knockout mice die from generalised lymphatic dysfunction. We show here that a homozygous pathogenic variant causes loss-of-function and results in severe early-onset hydrops fetalis. This is the first report of an autosomal recessive ANGPT2-related disorder in humans.

Spondyloocular Syndrome: A Novel XYLT2 Variant with Description of the Neonatal Phenotype

Spondyloocular syndrome (SOS) is a skeletal disorder caused by pathogenic variants in XYLT2 gene encoding a xylotransferase involved in the biosynthesis of proteoglycans. This condition, with autosomal recessive inheritance, has a high phenotypic variability. It is characterized by bone abnormalities (osteoporosis, fractures), eye and cardiac defects, hearing impairment, and varying degrees of developmental delay. Until now only 20 mutated individuals have been reported worldwide. Here, we describe two siblings from consanguineous healthy parents in which a novel homozygous frameshift variant c.1586dup p(Thr530Hisfs*) in the XYLT2 gene was detected by exome sequencing (ES). The first patient (9 years) presented short stature with skeletal defects, long face, hearing loss and cataract. The second patient, evaluated at a few days of life, showed macrosomia, diffuse hypertrichosis on the back, overabundant skin in the retronucal area, flattened facial profile with drooping cheeks, elongated eyelid rims, wide and flattened nasal bridge and turned down corners of the mouth. During the prenatal period, high nuchal translucency and intestinal hyperechogenicity were observed at ultrasound. In conclusion, these two siblings with a novel pathogenic variant in XYLT2 further expand the clinical and mutational spectrum of SOS.

Isolated Increased Nuchal Translucency in First Trimester Ultrasound Scan: Diagnostic Yield of Prenatal Microarray and Outcome of Pregnancy

Background: Increased nuchal translucency (NT) is associated with aneuploidy. When the karyotype is normal, fetuses are still at risk for structural anomalies and genetic syndromes. Our study researched the diagnostic yield of prenatal microarray in a cohort of fetuses with isolated increased NT (defined as NT ≥ 3.5 mm) and questioned whether prenatal microarray is a useful tool in determining the adverse outcomes of the pregnancy.Materials and Methods: A prospective study was performed, in which 166 women, pregnant with a fetus with isolated increased NT (ranging from 3.5 to 14.3 mm with a mean of 5.4 mm) were offered karyotyping and subsequent prenatal microarray when karyotype was normal. Additionally, all ongoing pregnancies of fetuses with normal karyotype were followed up with regard to postnatal outcome. The follow-up time after birth was maximally 4 years.Results: Totally, 149 of 166 women opted for prenatal testing. Seventy-seven fetuses showed normal karyotype (52%). Totally, 73 of 77 fetuses with normal karyotype did not show additional anomalies on an early first trimester ultrasound. Totally, 40 of 73 fetuses received prenatal microarray of whom 3 fetuses had an abnormal microarray result: two pathogenic findings (2/40) and one incidental carrier finding. In 73 fetuses with an isolated increased NT, 21 pregnancies showed abnormal postnatal outcome (21/73, 28.8%), 29 had a normal outcome (29/73, 40%), and 23 were lost to follow-up (23/73, 31.5%). Seven out of 73 live-born children showed an adverse outcome (9.6%).Conclusions: Prenatal microarray in fetuses with isolated increased NT had a 5% (2/40) increased diagnostic yield compared to conventional karyotyping. Even with a normal microarray, fetuses with an isolated increased NT had a 28.8% risk of either pregnancy loss or an affected child.