Clinical application of serological screening and non-invasive prenatal testing (NIPT) both have difficulties to attain high detection rate and low cost. For its advantages of high detection rate, high sensitivity, simplicity, short turnaround time and low cost, digital PCR (dPCR) has provided a new choice for prenatal screening of trisomies 21, 18 and 13. To standardize the application of dPCR for prenatal screening, we have formulated this consensus by referring to relevant guidelines, expert consensus and latest literature, which has covered the basic requirements, application scope, pre-testing service, testing procedure, report interpretation, genetic counseling, and limitations for this technology.

OBJECTIVE: To assess the value of copy number variation sequencing (CNV-seq) for the diagnosis of children with disorders of sex development (DSD). METHODS: Five children with DSD who presented at the First Affiliated Hospital of Zhengzhou University from October 2019 to October 2020 were enrolled. In addition to chromosomal karyotyping, whole exome sequencing (WES), SRY gene testing, and CNV-seq were also carried out. RESULTS: Child 1 and 2 had a social gender of female, whilst their karyotypes were both 46,XY. No pathogenic variant was identified by WES. The results of CNV-seq were 46,XY,+Y (1.4) and 46,XY,-Y (0.75), respectively. The remaining three children have all carried an abnormal chromosome Y. Based on the results of CNV-seq, their karyotypes were respectively verified as 45,X[60]/46,X,del(Y)(q11.221)[40], 45,X,16qh+[76]/46,X,del(Y)(q11.222),16qh+[24], and 45,X[75]/46,XY[25]. CONCLUSION CNV-seq may be used to verify the CNVs on the Y chromosome among children with DSD and identify the abnormal chromosome in those with 45,X/46,XY. Above results have provided a basis for the clinical diagnosis and treatment of such children.
Humans ; Child ; Female ; DNA Copy Number Variations ; Chromosome Aberrations ; Karyotyping ; Exome Sequencing ; Disorders of Sex Development/genetics*

OBJECTIVE: To explore the genetic basis for a rare case with Disorder of sex development. METHODS: Clinical data of the patient was collected. Chromosomal karyotyping, SRY gene testing, whole exome sequencing (WES), low-coverage massively parallel copy number variation sequencing (CNV-seq), fluorescence in situ hybridization (FISH), and whole genome sequencing (WGS) were carried out. RESULTS: The patient, a 14-year-old female, had manifested short stature and dysplasia of second sex characteristics. She was found to have a 46,XY karyotype and positive for the SRY gene. No pathogenic variant was found by WES, except a duplication at Yp11.32q12. The result of CNV-seq was 47,XYY. FISH has confirmed mosaicism for a dicentric Y chromosome. A 23.66 Mb duplication on Yp11.32q11.223 and a 5.16 Mb deletion on Yq11.223q11.23 were found by WGS. The breakpoint was mapped at chrY: 23656267. The patient's karyotype was ultimately determined as 46,X,psu idic(Y)(q11.223)/46,X,del(Y)(q11.223). CONCLUSION The combination of multiple methods has facilitated clarification of the genetic etiology in this patient, which has provided a reference for the clinical diagnosis and treatment.
Female ; Humans ; Adolescent ; DNA Copy Number Variations ; In Situ Hybridization, Fluorescence ; Y Chromosome ; Sexual Development ; Mosaicism

OBJECTIVE: To explore the cause for a twin pregnancy with false negative result for 22q11.2 deletion syndrome by expanded non-invasive prenatal testing (NIPT-plus). METHODS: A pregnant woman with twin pregnancy through in-vitro fertilization and negative result of NIPT-plus was selected as the study subject. Amniocentesis was conducted after ultrasonic finding of fetal abnormalities. In addition to conventional G-banded karyotyping, copy number variation sequencing (CNV-Seq) was used to detect chromosomal microdeletion and microduplication. Clinical data of the woman were analyzed to explore the reasons underlying the false negative result. RESULTS: NIPT-plus has yielded a negative result with 11.77 Mb unique reads and 3.05% fetal fraction. Both fetuses had a normal karyotype (46,XY and 46,XX). CNV-seq indicated that one of the fetuses was normal, whilst the other was diagnosed with a 2.58 Mb deletion in the 22q11.2 region. CONCLUSION The false negative result may be attributed to the combined influence of low fetal fraction, high BMI, twin pregnancy through IVF and a relatively small deletion fragment. Ultrasonography exam following a low-risk result of NIPT-plus should not be neglected.
Pregnancy ; Female ; Humans ; Prenatal Diagnosis ; Pregnancy, Twin/genetics* ; DiGeorge Syndrome/genetics* ; DNA Copy Number Variations ; Amniocentesis

Objective:To summarize initial experience of applying nanopore third-generation sequencing detection method (nanopore sequencing) for genetic diagnosis of non-classical 21 hydroxylase deficiency (NC 21-OHD), and to explore its performance and application prospects.Methods:Clinical data of the two NC 21-OHD patients, who were hospitalized at the First Affiliated Hospital of Zhengzhou University in May 2019, were collected. Peripheral venous blood was collected and genome DNA extracted. Genetic variants was detected by nanopore sequencing and underwent bioinformatic analysis. Pathogenetic mutations in CYP21A2 gene were validated with PCR-sanger sequencing in the two patients and their parents.Results:The average reads length and sequence depth in the patient one was 12, 792 bp and 27.19×. The average reads length and sequence depth in the patient two was 13, 123 bp and 21.34×. Compound variants of c.293-13C>G/c.844G>T (p.Val282Leu) and c.332_339delGAGACTAC (p.Gly111Valfs)/c.844G>T (p.Val282Leu) were detected in these two patients, which were consistent with clinical phenotype of NC 21-OHD. Further analysis showed that c.293-13C>G mutation was inherited from her father and c.844G>T (p.Val282Leu) mutation was inherited from her mother for the patient one. The c.844G>T (p.Val282Leu) mutation was inherited from her father and c.332_339delGAGACTAC (p.Gly111Valfs) mutation from her mother.Conclusions:The heterozygous mutations in CYP21A2 gene are the cause of NC 21-OHD in these two patients. Nanopore sequencing technique is a reliable new detection method for patients with NC 21-OHD.

OBJECTIVE: To analyze the result of prenatal diagnosis and outcome of pregnancy for fetuses with rare autosomal trisomies (RATs) suggested by non-invasive prenatal testing (NIPT). METHODS: A total of 69 608 pregnant women who underwent NIPT at Genetics and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University from January 2016 to December 2020 were selected as study subjects. The result of prenatal diagnosis and outcome of pregnancy for those with a high risk for RATs were retrospectively analyzed. RESULTS: Among the 69 608 pregnant women, the positive rate of NIPT for high-risk RATs was 0.23% (161/69 608), with trisomy 7 (17.4%, 28/161) and trisomy 8 (12.4%, 20/161) being the most common, and trisomy 17 (0.6%, 1/161) being the rarest. For 98 women who had accepted invasive prenatal diagnosis, 12 fetal chromosomal abnormalities were confirmed, and in 5 cases the results were consistent with those of NIPT, which yielded a positive predictive value of 5.26%. Among the 161 women with a high risk for RATs, 153 (95%) were successfully followed up. 139 fetuses were ultimately born, with only one being clinically abnormal. CONCLUSION Most women with a high risk for RATs by NIPT have good pregnancy outcomes. Invasive prenatal diagnosis or serial ultrasonography to monitor fetal growth, instead of direct termination of pregnancy, is recommended.
Pregnancy ; Female ; Humans ; Trisomy/genetics* ; Pregnancy Outcome ; Retrospective Studies ; Prenatal Diagnosis/methods* ; Fetus ; Trisomy 18 Syndrome/genetics* ; Aneuploidy

OBJECTIVE: To assess the value of re-sampling for patients who had failed non-invasive prenatal testing (NIPT) due to low cell-free fetal DNA (cffDNA) fraction. METHODS: Clinical data of 20 387 patients undergoing NIPT test was reviewed. The patients were re-sampled when initial blood test did not yield a result due to cffDNA fraction. The results were analyzed, and the outcome of pregnancy was followed up. RESULTS: Among all samples, 17 (0.08%) had failed to yield a result due to low cffDNA fraction, all of which accepted re-sampling. A result was attained in 16 cases, with a success rate of 94.12%. Only one sample had failed the re-test. CONCLUSION For patients who had failed the initial NIPT due to low cffDNA fraction, re-sampling should be considered with gestational week and ultrasound results taken into consideration.
Aneuploidy ; Cell-Free Nucleic Acids/genetics* ; DNA/genetics* ; Female ; Fetus ; Humans ; Pregnancy ; Prenatal Diagnosis

Apparently balanced chromosomal structural rearrangements are known to cause male infertility and account for approximately 1% of azoospermia or severe oligospermia. However, the underlying mechanisms of pathogenesis and etiologies are still largely unknown. Herein, we investigated apparently balanced interchromosomal structural rearrangements in six cases with azoospermia/severe oligospermia to comprehensively identify and delineate cryptic structural rearrangements and the related copy number variants. In addition, high read-depth genome sequencing (GS) (30-fold) was performed to investigate point mutations causative of male infertility. Mate-pair GS (4-fold) revealed additional structural rearrangements and/or copy number changes in 5 of 6 cases and detected a total of 48 rearrangements. Overall, the breakpoints caused truncations of 30 RefSeq genes, five of which were associated with spermatogenesis. Furthermore, the breakpoints disrupted 43 topological-associated domains. Direct disruptions or potential dysregulations of genes, which play potential roles in male germ cell development, apoptosis, and spermatogenesis, were found in all cases (n = 6). In addition, high read-depth GS detected dual molecular findings in case MI6, involving a complex rearrangement and two point mutations in the gene DNAH1. Overall, our study provided the molecular characteristics of apparently balanced interchromosomal structural rearrangements in patients with male infertility. We demonstrated the complexity of chromosomal structural rearrangements, potential gene disruptions/dysregulation and single-gene mutations could be the contributing mechanisms underlie male infertility.
Azoospermia/genetics* ; Chromosome Aberrations ; Humans ; Infertility, Male/genetics* ; Male ; Oligospermia/genetics* ; Translocation, Genetic

OBJECTIVE: To assess the value of low-depth whole-genome copy number variation sequencing (CNV-seq) for the analysis of chromosomal copy number variations among fetuses with echogenic bowel (EB). METHODS: A total of 163 fetuses were included in this study. Amniotic fluid (162 cases) or chorionic villi (1 case) were collected and subjected to CNV-seq for the analysis of CNVs. RESULTS: Thirteen (8.0%) pathogenic CNVs were detected, including 9 (5.5%) aneuploidies and 4 (2.4%) CNVs. The detection rate of the isolated EB group and combined EB group were 1.7% (1/58) and 11.4% (12/105), respectively. There was a significant difference between the two groups (P < 0.05). A Xp22.1 duplication was detected in both groups, and the fetuses were predicted as female DMD carriers and born healthy. Nine cases of aneuploidies and 2 (likely) pathogenic CNVs were identified in the combined EB group, all of them have warranted induced labor. CONCLUSION The prevalence of chromosomal aneuploidies and pathogenic CNVs in fetuses with combined EB was much higher than isolated EB, and most of them may warrant termination of pregnancy. Compared with isolated EB, more attention should be paid to combined EB, for which prenatal diagnosis and genetic counseling should be carried out in time.
Amniotic Fluid ; Aneuploidy ; Chromosome Aberrations ; DNA Copy Number Variations ; Echogenic Bowel ; Female ; Humans ; Pregnancy ; Prenatal Diagnosis ; Technology

OBJECTIVE: To explore the clinical characteristics and molecular pathogenesis of a child with autosomal dominant polycystic kidney disease (ARPKD). METHODS: Prenatal ultrasound, clinical feature and family history of the child were analyzed. Whole exome sequencing was carried out for the child. Candidate variants were verified by Sanger sequencing. RESULTS: The child has featured premature birth with very low weight, neonatal respiratory distress, metabolic acidosis, and congenital nephrotic syndrome. Gene sequencing revealed that he has harbored compound heterozygous variants of the PKHD1 gene (NM_138694), including c.3885T>A (p.Tyr1295*) in exon 32 and c.7812_7816dupTGATA (p.Thr2606Metfs*63) in exon 49, which were respectively inherited from his mother and father. CONCLUSION The compound heterozygous variants of the PKHD1 gene probably underlay the disease in this child.
Child ; Exons ; Female ; Genetic Testing ; Humans ; Infant, Newborn ; Male ; Mutation ; Polycystic Kidney, Autosomal Recessive/genetics* ; Pregnancy ; Receptors, Cell Surface/genetics*