Prenatal diagnosis of fetuses with Emanuel syndrome: Results of ultrasound examination and invasive genetic testing.

OBJECTIVE: To investigate prenatal manifestations of Emanuel syndrome (ES) by retrospectively analyzing the results of prenatal diagnosis. METHODS: Thirteen fetuses were collected from five hospitals, of which six were confirmed with 47,der(22)t(11;22; ES) by karyotype and chromosomal microarray analysis (CMA). Seven were diagnosed with 46,t(11;22) balanced translocations by karyotype, including one de novo mosaic 46,XX,t(11;22). In 3/7, CMA was performed but did not identify chromosomal imbalances. The results of prenatal diagnoses were reviewed, including ultrasound examinations and genetic testing. RESULTS: In ES fetuses, the derivative 22 was consistently inherited from the mother, while in the balanced translocation group, the t(11;22) chromosome was of paternal origin in 3/6 cases, All ES fetuses presented with multiple abnormalities by ultrasound examinations. Diaphragm hernia (3/6), Dandy-Walker complex (3/6), and kidney aplasia (3/6), were the most common ultrasound findings. Sonographic soft markers such as increased nuchal translucency, increased nuchal fold thickness appeared in 3 cases and all of these were associated with other anomalies. However, none of the ultrasound findings differentiated ES from other genetic syndromes during fetal period. CONCLUSIONS: In this series, in fetuses with a der(22), the derivative chromosome was consistently of maternal origin. In contrast, 46,t(11;22) balanced translocations were of maternal or paternal origin. The results contribute to the literature regarding the fetal phenotype of ES. Due to the absence of specific features distinguishing ES from other genetic syndromes, confirming the diagnosis through invasive genetic testing is necessary.

The Association between Maternal/Fetal Insulin Receptor Substrate 1 Gene Polymorphism rs1801278 and Gestational Diabetes Mellitus in a Chinese Population.

OBJECTIVES: Insulin receptor substrate 1 (IRS1) is a crucial factor in the insulin signaling pathway. IRS1 gene polymorphism rs1801278 in mothers has been reported to be associated with gestational diabetes mellitus (GDM). However, it is not clear whether IRS1 gene polymorphism rs1801278 in fetuses is associated with their mothers' GDM morbidity. The purpose of this study is to analyze the association between maternal, fetal, or maternal/fetal IRS1 gene polymorphism rs1801278 and GDM risk. DESIGN: The study was a single-center, prospective cohort study. In total, 213 pairs of GDM mothers/fetuses and 191 pairs of control mothers/fetuses were included in this study. They were recruited after they underwent oral glucose tolerance test during 24-28 weeks of gestation and followed up until delivery. All participants received the conventional interventions (diet and exercise), and no special therapy except routine treatment. METHODS: A total of 213 pairs of GDM mothers/fetuses and 191 pairs of normal blood glucose pregnant mothers/fetuses were ge-notyped using PCR and DNA sequencing from January 2015 to September 2016. Maternal/fetal IRS1 gene polymorphism rs1801278 was analyzed and compared between 2 groups. RESULTS: There were no significant differences in the frequency of individual mothers' or fetuses' IRS1 rs1801278 polymorphisms between 2 groups; if both the mothers and fetuses carried A allele, significantly lower GDM morbidity was observed in the mothers. LIMITATIONS: The sample size was relatively small as a single-center study. CONCLUSIONS: Our study suggested that maternal/fetal rs1801278 polymorphism of IRS1 is a modulating factor in GDM; both mothers/fetuses carrying the A allele of rs1801278 may protect the mothers against the development of GDM.

Low-pass whole-genome sequencing in clinical cytogenetics: a validated approach.

PURPOSE: Chromosomal microarray analysis is the gold standard for copy-number variant (CNV) detection in prenatal and postnatal diagnosis. We aimed to determine whether next-generation sequencing (NGS) technology could be an alternative method for CNV detection in routine clinical application. METHODS: Genome-wide CNV analysis (>50 kb) was performed on a multicenter group of 570 patients using a low-coverage whole-genome sequencing pipeline. These samples were referred for chromosomal analysis; CNVs (i.e., pathogenic CNVs, pCNVs) were classified according to the American College of Medical Genetics and Genomics guidelines. RESULTS: Overall, a total of 198 abortuses, 37 stillbirths, 149 prenatal, and 186 postnatal samples were tested. Our approach yielded results in 549 samples (96.3%). In addition to 119 subjects with aneuploidies, 103 pCNVs (74 losses and 29 gains) were identified in 82 samples, giving diagnostic yields of 53.2% (95% confidence interval: 45.8, 60.5), 14.7% (5.0, 31.1), 28.5% (21.1, 36.6), and 30.1% (23.6, 37.3) in each group, respectively. Mosaicism was observed at a level as low as 25%. CONCLUSIONS: Patients with chromosomal diseases or microdeletion/microduplication syndromes were diagnosed using a high-resolution genome-wide method. Our study revealed the potential of NGS to facilitate genetic diagnoses that were not evident in the prenatal and postnatal groups.Genet Med 18 9, 940-948.

Placental methylation markers in normal and trisomy 21 tissues.

OBJECTIVE: The objective of this study is to combine multiplex ligation-dependent probe amplification (MLPA) and bisulfite sequencing to determine DNA methylation markers for noninvasive prenatal diagnosis of Down syndrome. METHODS: DNA methylation ratios (MR) of four fragments (CGI149, CGI045, HLCS-1, and HLCS-2) on chromosome 21 were evaluated in blood cells from 13 nonpregnant women, 15 euploidies, and 11 Down Syndrome (DS) placentae. Ratios were measured by bisulfite sequencing and methylation-specific (MS)-MLPA. RESULTS: The MS-MLPA and bisulfite sequencing results were concordant. CGI149, CGI045, and HLCS-2 were unmethylated in all nonpregnant blood cells. CGI149, CGI045, HLCS-1, and HLCS-2 were methylated in most of the euploid (13, 11, 15, and 15, respectively) and DS placentae (10, 11, 11, and 11, respectively). The median placental DNA MR in CGI149 was 0.4578 (interquartile range, 0.3568-0.5169) and 0.5918 (interquartile range, 0.5618-0.6659) in euploid and DS placentae, respectively (p = 0.001). Using placental MR at 0.5390 as a threshold, we detected DS at 90.9% sensitivity and 93.3% specificity. CONCLUSION: The MS-MLPA is an effective alternative to bisulfite sequencing in assessing placental MR. CGI149 is a potential marker for the noninvasive diagnosis of Down syndrome.

Identification of a novel COL10A1: c.1952 G>T variant in a family with Schmid metaphyseal chondrodysplasia and development of a noninvasive prenatal testing method.

BACKGROUND: The collagen alpha-1(X) chain gene (COL10A1) is a known causative gene for Schmid metaphyseal chondrodysplasia (SMCD). This study clinically examined a Chinese family (n = 42) for SMCD and inheritance pattern. Fifteen individuals were diagnosed with SMCD based on characteristic skeletal phenotypes with autosomal dominant inheritance mode. METHODS: Four clinically diagnosed patients and three healthy relatives were selected for subsequent genetic tests. Trio-whole exome sequencing (Trio-WES) followed by Sanger sequencing and familial co-segregation analysis were performed to identify SMCD-associated variants. RESULTS: COL10A1 (NM_000493.4):c.1952 G>T(p.Trp651Leu) variant was detected only in the four patients and not in the three healthy relatives. The variant was evaluated as "likely pathogenic" according to the American College of Medical Genetics and Genomics variation classification guidelines with evidence of PM2, PM5, PP1, and PP3. To test the presence of the target variant in proband's fetal offspring, we developed a noninvasive prenatal testing method by extracting cell-free fetal DNA in maternal plasma followed by high-depth sequencing. The variant was also detected in the fetus and later confirmed by amniocentesis. CONCLUSION: We identified a new disease-causing variant in COL10A1. Cell-free fetal DNA in maternal peripheral blood can be used as the rapid and noninvasive prenatal diagnostic method to detect the pathogenic/or likely pathogenic variant.

Non­invasive prenatal diagnosis of thalassemia through multiplex PCR, target capture and next­generation sequencing.

Prenatal clinical detection of thalassemia involves gap­PCR and reverse dot blot (RDB) analysis of fetal DNA acquired through invasive methods. The present study aimed to develop a non­invasive prenatal diagnostic method for thalassemia based on next­generation sequencing (NGS). A total of eight families with proband children with thalassemia were recruited for the study during a subsequent pregnancy. The sequence of the thalassemia genes of the parents and proband were determined using NGS, based on a thalassemia AmpliSeq panel. Cell­free plasma DNA from pregnant women related to the aforementioned proband was analyzed using an NGS panel, based on thalassemia­associated capture probes. Heterozygous single nucleotide polymorphisms within the 10 kb regions flanking exons of the targeted thalassemia genes were acquired using probes or AmpliSeq and employed for parental haplotype construction using Trio­based panel sequencing. The fetal haplotype was deduced from the parental haplotypes and relative haplotype dosage, and subsequently validated using gap­PCR and RDB, based on invasively sampled amniotic fluid. A non­invasive prenatal diagnosis procedure from maternal plasma fetal DNA was successfully developed based on haplotype analysis. The deduced haplotypes of eight fetuses were identical to the results of invasive prenatal diagnosis procedures, with an accuracy rate of 100%. Taken together, the present study demonstrated the potential for non­invasive prenatal diagnosis of α­ and ß­thalassemia using NGS and haplotype­assisted analysis.

[Children's hearing behavior observations and high risk individual genetic screening for late-onset hearing loss early detection and intervention exploring a basic-level hospitals model].

OBJECTIVE: To explore the methods to detect and intervene children's late-onset hearing loss early which are suitable for basic-level hospitals. METHOD: Udiology and imaging diagnosis had been given to the children who passed the newborn hearing screening but showed auditory behavior disorders in the growth process, and individualized interventions were given according to the results of diagnosis. Seven children with high risk for hereditary deafness were sent to superior hospital and had molecular screening of common mutations of inherited deafness carried out, then corresponding prevention guidance and intervention were given to them. RESULT: Fifty-two cases with late-onset hearing loss or verbal disorders were detected by auditory behavior observations,including 4 cases of auditory neuropathy, 4 cases of unilateral sensorineural deafness, 27 cases of secretory otitis media. 13 cases of bilateral sensorineural deafness and 4 cases of autism. Seven newborns with high risk of hereditary deafness were sent to the Third Affiliated Hospital of Sun Yat-Sen University and received molecular screening of common mutations of inherited deafness. One case with GJB2 compound heterozygous mutations was detected and followed up to 4 years old, he was found bilateral moderate hearing loss and accepted the hearing aids at 2 years old. Mitochondrial DNA 1555 a > G heterogeneity mutation in 2 cases and GJB2 235 delC single heterozygous mutations in 3 cases, no mutation in 1 case, all these 6 cases have been followed-up until now, their hearing are normal. CONCLUSION: Children's auditory behavior observations and the superior hospitals referral performing high risk individual screening for newborns with high risk for hereditary deafness can detect children's late-onset hearing loss in time, this model is suitable for basic-level hospitals.