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Objective: To explore the molecular basis for an individual with postnatal deafness and provide genetic counseling for her family., Methods: Following extraction of genomic DNA from peripheral blood samples, 127 genes associated with deafness were subjected to targeted capturing and next generation sequencing. Suspected mutation was verified by Sanger sequencing., Results: The proband was found to carry a homozygous c.1893C>A mutation in the TECTA gene, which is located in the tectorial membrane of inner ear and may cause premature termination of translation of TECTA protein. In addition, two heterozygous mutations, c.13010C>T and c.12790G>A, were found in the USH2A gene. Whilst the former is likely to be pathogenic, the latter has unknown clinical significance. Further analysis suggested that all three mutations have derived from the parents of the proband., Conclusion: The homozygous c.1893C>A mutation of the TECTA gene probably underlies the proband's hearing loss which conformed to an autosomal recessive inheritance.

Objective: To determine the origin of a supernumerary small marker chromosome found in a fetus using prenatal BACs-on-Beads (BoBs) and single nucleotide polymorphism array (SNP-array) assays., Methods: The fetal sample was subjected to chromosomal karyotyping and BoBs analysis, and the results were validated with genome-wide scanning using a SNP microarray., Results: The fetus was found to have a 47,XX,+mar karyotype. BoBs analysis indicated that there was an amplification between 18p11.32 and 18p11.21, which was verified by the SNP-array assay as a 18.3 Mb duplication occurring at 18p11.32q11.1., Conclusion: The karyotype of the fetus was determined as 47,XX,+der18(18p11.32?18q11.1::18q11.1?18p11.32). The duplication has involved important genes including SMCHD1, LPIN2 and TGIF1, which may result in severe malformations in the fetus.

Objective: To evaluate the efficiency of cell-free fetal DNA detection as a non-invasive prenatal screening (NIPS) method for women of advanced maternal age., Methods: A total of 10 584 women of advanced maternal age who received NIPS were recruited from the Women's Hospital, Zhejiang University School of Medicine and Jiaxing Maternal and Child Health Hospital during February 2015 and September 2016. The pregnancy outcome was followed-up. The sensitivity, specificity, positive and negative predictive value of fetal chromosomal aneuploidy detected in NIPS were analyzed. And the relationship between maternal age and fetal common chromosomal aneuploidy was analyzed., Results: The sensitivity, specificity, positive and negative predictive value of NIPS were 100.00%, 99.96%, 91.67%, 100.00% for trisomy 21, 100.00%, 99.93%, 68.18%, 100.00% for trisomy 18, and 100.00%, 99.97%, 25.00%, 100.00% for trisomy 13. High-risk rate and true positive rate of trisomy 21 were positively correlated with the maternal age (all P <0.01). There were significant differences in high-risk rate and true positive rate between 35-37 year old groups and 38-40 year old groups (all P <0.05). Such difference was also found in high-risk rate between 38-40 year old group and ≥ 41 year old group ( P <0.05), but not in true positive rate between two groups ( P >0.05)., Conclusions: NIPS is effective for fetal chromosomal aneuploidy screening in women of advanced maternal age. For women under 38 years of age, NIPS is preferred; for women of 41 and above, invasive diagnostic methods are suggested; and for women between 38-41 years old, the option can be determined by themselves after risks and advantages were fully informed.

Objective: To explore the origin of a supernumerary small marker chromosome (sSMC) in a fetus, and to assess the feasibility of single nucleotide polymorphism array (SNP-array) for prenatal diagnosis., Methods: The fetal sample was subjected to karyotyping analysis. The identified sSMC was subjected to genome-wide scan using a SNP microarray chip. The results were validated with fluorescence in situ hybridization (FISH)., Results: The karyotype of the fetus was determined as 47,XX,+mar, which was verified by SNP microarray chip analysis as a 34.6 Mb duplication in 12p13.33p11.1. FISH analysis confirmed that the sSMC has originated from chromosome 12p., Conclusion: The karyotype of the fetus was determined as 47,XX,+i(12)(p10). Tetrasomy 12p is reported to be a marker for Pallister-Killian syndrome, which may result in multi-system anomalies. SNP-array analysis can simultaneously detect microdeletions and microduplications, which may be used for prenatal diagnosis of suspected cases.

Objective: To explore the genetic causes for a child with multiple congenital malformations and epilepsy through analysis of copy number variations, and to correlate the genotype with the phenotype., Methods: G-banding karyotyping was performed on the child and her parents. Single nucleotide polymorphisms array (SNP-array) was used to map the exact chromosomal breakpoints in the proband. The result was validated with fluorescence in situ hybridization (FISH)., Results: G banding analysis suggested that the proband had a karyotype of 46,XX,del(4)(p15), while both of his parents had a normal karyotype. SNP-array has identified a hemizygous deletion of 13.3 Mb on chromosome 4p16.3p15.33, which has been implicated in Wolf-Hirschhorn syndrome. FISH assay has confirmed the de novo origin of the deletion, with the karyotype and clinical phenotype of both parents taken into consideration., Conclusion: A case of Wolf-Hirschhorn syndrome has been diagnosed by clinical manifestation and karyotyping analysis. Compared with conventional karyotyping analysis, SNP-array has greater resolution and accuracy, and can provide useful information for genetic counseling.

Objective: To explore the genetic cause for a child with mental retardation, developmental delay and multi-systemic developmental disorders by analyzing the copy number variations (CNVs) and correlating the genotype with the phenotype., Methods: Routine G-banding was performed to analyze the karyotype of the patient and her parents. In addition, single nucleotide polymorphisms array (SNP-array) was used to determine the CNVs, which was confirmed by fluorescence in situ hybridization (FISH)., Results: No karyotypic abnormality was detected upon chromosome analysis. However, SNP-array has identified a de novo hemizygous deletion of 1673 kb on chromosome region 7q11.23, which has been associated with Williams-Beuren syndrome. The microdeletion was confirmed by FISH testing., Conclusion: A child with Williams-Beuren syndrome has been diagnosed by SNP-array and FISH. The de novo 7q11.23 microdeletion probably underlies the clinical manifestation of the patient. Compared with routine karyotype analysis, SNP-array is more useful for diagnosing children with multiple congenital anomalies with unclear etiology.

Objective: To perform non-invasive prenatal diagnosis (NIPD) of chromosome aneuploidy by detecting free DNA in maternal peripheral plasma by massively parallel genomic sequencing and determine the feasibility of detecting cell-free fetal DNA in chromosomal copy., Methods: The plasma samples from 1 264 gravidas were collected from February 2012 to July 2013 at our center. Those pregnant women with a gestational age of 13 to 33 weeks having high risks in serological screening or aged over 35 years or abnormal fetus on ultrasonography. The peripheral venous blood samples were drawn from pregnant women and plasma DNA was extracted for preparing a sequencing library. By using Illumina HiSeq2000, high-throughput sequencing was performed. Amnocentesis and karyotypic analysis were conducted for positive cases and those with negative results were followed up., Results: By massively parallel genomic sequencing, 20 of them showed positive results. By the standard of chromosomal karyotypic analysis, there were 21 positive cases of 13 trisomy and the diagnostic accordance rate was 100%. Among 18 positive cases of 6 trisomy, there were amniocentesis (n = 5, except for one dead fetus), trisomy 18 (n = 4) and normal karyotype with placenta chimera (n = 1). One positive case of 13 trisomy was in accordance with karyotypic analysis., Conclusion: Massively parallel sequencing for NIPD may be used as further screening for pregnant women with high risks of serological screening. And this technology is highly consistent with karyotypic analysis in terms of sensitivity and specificity.