Objective:To analyze the results of prenatal diagnosis and outcome of pregnancy for women with a high risk for fetal aneuploidies.Methods:A total of 747 cases of prenatal diagnosis by amniocentesis due to high risks by non-invasive prenatal testing (NIPT) were selected from January 2015 to March 2022 in the Drum Tower Hospital Affiliated to Nanjing University Medical School. The amniotic fluid samples were subjected to chromosomal karyotyping and/or chromosomal microarray analysis. All cases were followed up by searching the birth information or telephone calls, and the results were recorded. 2 test or F test were used for comparing the difference between the groups.Results:Among the 747 pregnant women with a high risk by NIPT, 387 were true positives, and the overall positive predictive value (PPV) was 51.81%. The PPVs for trisomy 21 (T21), trisomy 18 (T18), trisomy 13 (T13) and sex chromosome aneuploidies (SCA) were 80.24% (199/248), 60% (48/80), 14% (7/50) and 38.97% (106/272), respectively. The PPV for T21 was significantly higher than T18 and T13 ( χ2= 85.216, P<0.0001). The PPV for other chromosomal aneuploidies and copy number variations (CNVs) were 11.11% (5/45) and 40.74% (22/52), respectively. The PPV for increased X chromosomes was significantly higher than X chromosome decreases (64.29% vs. 22.22%, χ2= 5.530, P<0.05). The overall PPV for elder women (≥ 35 years old) was significantly higher than younger women (69.35% vs. 42.39%, χ2= 49.440, P<0.0001). For T21 and T18, the PPV of Z ≥ 10 group was significantly higher than that for 3 ≤ Z < 5 group or 5 ≤ Z < 10 group ( P<0.05). Among 52 cases with a high risk for CNVs, the PPV for the ≤ 5 Mb group was significantly higher than the 5 Mb < CNVs < 10 Mb or > 10 Mb groups (60% vs. 30%和60% vs. 23.53%, P<0.05). Among the 387 true positive cases, 322 had opted for induced labor, 53 had delivered with no abnormal growth and development, and 12 were lost during the follow-up. Conclusion:The PPVs for common chromosomal aneuploidies are related to the age and Z value of the pregnant women, which were higher in the elder group and higher Z value group. In addition, the PPV is associated with high risk types. The PPV for T21 was higher than T18 and T13, and that for 45, X was lower than 47, XXX, 47, XYY or 47, XXY syndrome. NIPT therefore has relatively high PPVs for the identification of chromosomal CNVs.

Objective:To explore the cause of inconsistency between the results of trisomy 7 by expanded non-invasive prenatal testing (NIPT-PLUS) and trisomy 18 by prenatal diagnosis.Methods:A pregnant woman who received genetic counseling at Jiaozuo Maternal and Child Health Care Hospital on July 5, 2020 was selected as the study subject. NIPT-PLUS, systematic ultrasound and interventional prenatal testing were carried out. The middle segment and root of umbilical cord, center and edge of the maternal and fatal surface of the placenta were sampled for the validation by copy number variation sequencing (CNV-seq).Results:The result of NIPT-PLUS indicated that the fetus has trisomy 7. Systematic ultrasound has shown multiple malformations including atrioventricular septal defect, horseshoe kidney, and rocker-bottom feet. However, QF-PCR, chromosomal karyotyping analysis, and CNV-seq of amniotic fluid samples all showed that the fetus was trisomy 18. Validation using multiple placental samples confirmed that the middle segment of the umbilical cord contains trisomy 18, the center of the placenta contained trisomy 7, and other placental sites were mosaicism for trisomy 7 and trisomy 18. Notably, the ratio of trisomy 18 became lower further away from the umbilical cord.Conclusion:The false positive results of trisomy 7 and false negative trisomy 18 by NIPT-PLUS was probably due to the existence of placental mosaicism. Strict prenatal diagnosis is required needed aneuploidy is detected by NIPT-PLUS to exclude the influence of placental mosaicisms.

Objective:To evaluate the feasibility of non-invasive prenatal testing (NIPT) for the screening of fetal chromosome aneuploidies in twin pregnancies.Methods:A total of 2 745 women with twin-pregnancies were subjected for NIPT screening. Chromosomal karyotyping and chromosomal microarray analysis (CMA) were carried out on amniotic fluid samples from those with a high risk for fetal chromosome aneuploidies, and the diagnosis and pregnancy outcome were followed up. The sensitivity, specificity, positive predictive value and false positive rate of the NIPT were calculated.Results:Compared with other chromosomal abnormalities, NIPT had a higher efficacy for trisomy 21 and sex chromosomal aneuploidy (SCA) in twin pregnancies (with sensitivity being 100%, 100%, and specificity being 99.93%, 99.9%, respectively). It is difficult to evaluate the efficacy for trisomies 18 and 13 due to the limited data. For chromosome microdeletions and microduplications spanning 15 ~ 21 Mb, NIPT also had a certain detection rate. Compared with women with natural conception, NIPT had a higher detection rate for those with twin pregnancies by assisted reproduction ( P < 0.05). Conclusion:It is feasible to use NIPT for the detection of chromosome aneuploidies in women with twin pregnancies.

Objective:To assess the effectiveness and feasibility of carrier detection for Spinal muscular atrophy (SMA) by using digital PCR assay.Methods:Peripheral blood samples were collected from 214 pregnant women who were routinely screened for SMA carriers, of which 204 were randomly selected samples and 10 were samples with known copy numbers of SMN1 exons 7 and 8. Samples with known copy numbers of SMN1 exons 7 and 8 were randomly mixed into the experiment to validate the performance of the digital PCR assay. The copy numbers of SMN1 exons 7 and 8 and SMN2 exons 7 and 8 in peripheral blood samples were detected by digital PCR assay. The results of SMN1 exons 7 and 8 were compared with those of the quantitative PCR method to assess the reliability and clinical performance of the digital PCR assay. Results:Among the 204 random samples, digital PCR has detected five samples with simultaneous heterozygous deletion of SMN1 exons 7 and 8, three samples with heterozygous deletion of SMN1 exon 8 only, and 196 samples with no deletion of SMN1 exons 7 and 8. Ten samples with known SMN1 exons 7 and 8 copy numbers were detected with the expected values. The digital PCR test results were fully consistent with that of the quantitative PCR. Conclusion:The results of digital PCR for the detection of copy number variation of SMN1 exons 7 and 8 were consistent with qPCR. Digital PCR assay was able to clearly distinguish the copy number of the target genes, therefore can be used for SMA carrier screening. Moreover, it can also detect copy number of SMN2 exons 7 and 8, which can provide more information for genetic counseling.

Objective:To explore the early neurodevelopmental features of young children with SYNGAP1 variants and their genotype-phenotype correlation. Methods:Young children with neurodevelopmental disorders (NDDs) (< 5 years old) who were referred to the Children′s Hospital Affiliated to the Capital Institute of Pediatrics between January 2019 and July 2022 were selected as the study subjects. All children had undergone whole-exome sequencing, comprehensive pediatric neuropsychological assessment, familial segregation analysis, and pathogenicity classification. Meanwhile, young Chinese NDD children (< 5 years old) with pathogenic/likely pathogenic SYNGAP1 variants were retrieved from the literature, with information including detailed clinical and genetic testing, neurodevelopmental quotient (DQ) of the Children Neuropsychological and Behavior Scale-Revision 2016 (CNBS-R2016). Children who did not have a detailed DQ but had their developmental status assessed by a medical professional were also included. The correlation between neurodevelopmental severity, comorbidity and SYNGAP1 variants were summarized. Results:Four young NDD children carrying SYNGAP1 variants were recruited (1 male and 3 females, with a mean age of 34.0 ± 18.2 months), among whom one harboring a novel variant (c.437C>G, p. S146*). Combined with 19 similar cases retrieved from the literature, 23 Chinese NDD young children were included in our study (8 males and 10 females, 5 with unknown sex, with a mean age of 37.1 ± 14.2 months). A loss of function (LOF) variant was found in 19 (82.6%) children. All of the children had presented global developmental delay (GDD) before the age of two. In addition, 16 (69.6%) had seizure/epilepsy at the age of 27.0 ± 12.1 months, among whom 15 had occurred independent of the global developmental delay. Myoclonic and absence were common types of seizures. Compared with those with variants of exons 8 to 15, the severity of developmental delay was milder among children with variants in exons 1 to 5. Conclusion:The early neurodevelopment features of the SYNGAP1 variants for young children (< 5 years old) have included global developmental delay and seizure/epilepsy. All of the children may present GDD before the age of two. The severity of developmental delay may be related to the type and location of the SYNGAP1 variants.

Objective:To study the trinucleotide repeats of GCN (GCA, GCT, GCC, GCG) encoding Alanine in exon 3 of the PHOX2B gene among healthy individuals from southwest China and two patients with Congenital central hypoventilation syndrome (CCHS). Methods:The number and sequence of the GCN repeats of the PHOX2B gene were analyzed by capillary electrophoresis, Sanger sequencing and cloning sequencing of 518 healthy individuals and two newborns with CCHS, respectively. Results:Among the 1036 alleles of the 518 healthy individuals, five alleles were identified, including (GCN) 7, (GCN) 13, (GCN) 14, (GCN) 15 and (GCN) 20. The frequency of the (GCN) 20 allele was the highest (94.79%). And five genotypes were identified, which included (GCN) 7/(GCN) 20, (GCN) 13/(GCN) 20, (GCN) 14/(GCN) 20, (GCN) 15/(GCN) 20, (GCN) 20/(GCN) 20. The homozygous genotypes were all (GCN) 20/(GCN) 20, and the carrier rate was 89.58%. Four GCN sequences of the (GCN) 20 homozygous genotypes were identified among the 464 healthy individuals. The GCN repeat numbers in the exon 3 of the PHOX2B gene showed no significant difference between the expected and observed values, and had fulfilled the, Hardy-Weinberg equilibrium. The genotypes of the two CCHS patients were (GCN) 20/(GCN) 25 and (GCN) 20/(GCN) 30, respectively. Conclusion:It is important to determine the GCN repeats and genotypic data of the exon 3 of the PHOX2B gene among the healthy individuals. The number of GCN repeats in 518 healthy individuals was all below 20. The selection of appropriate methods can accurately detect the polyalanine repeat mutations (PARMs) of the PHOX2B gene, which is conducive to the early diagnosis, intervention and treatment of CCHS.

Objective:To obtain skin-derived induced pluripotent stem cells (iPSCs) from an Osteogenesis imperfecta (OI) patient carrying WNT1c.677C>T mutation in order to provide a new cell model for investigating the underlying molecular mechanism and stem cell therapy for OI. Methods:The pathogenic variant of the patient was identified by Sanger sequencing. With informed consent from the patient, skin tissue was biopsied, and primary skin fibroblasts were cultured. Skin fibroblasts were induced into iPSCs using Sendai virus-mediated non-genomic integration reprogramming method. The iPSC cell lines were characterized for pluripotency, differentiation capacity, and karyotyping assay.Results:The patient was found to carry homozygous missense c. 677C>T (p.Ser226Leu) mutation of the WNT1 gene. The established iPSC lines possessed self-renewal and capacity for in vitro differentiation. It also has a diploid karyotype (46, XX). Conclusion:A patient-specific WNT1 gene mutation ( WNT1c.677C>T) iPSC line was established, which can provide a cell model for the study of OI caused by the mutation.

Objective:To study the genetic polymorphisms of short-tandem repeats (STR) for the D13S317 locus among an ethnic Han Chinese population and verify a novel tri-allelic pattern identified for the locus. Methods:A total of 378 paternity test cases from Guangdong Forensic Authentication Institute from October 17, 2017 to December 28, 2017 were selected as the study subjects. A GlobalFiler? Express kit was used for the STR genotyping. Samples suspected for having a novel tri-allelic pattern were verified with a PowerPlex ? 21 kit. Potential variant of the primer-binding region and flanking sequences underlying the tri-allelic pattern was excluded by molecular cloning and sequencing. Results:Six alleles were detected for the D13S317 locus, with the characteristic distribution frequencies being 8 (29.1%), 9 (13.1%), 10 (15.21%), 11 (24.21%), 12 (13.89%) and 13 (3.44%), respectively. In one of the families, the D13S317 locus of the proband was suspected to harbor a triband allele (8, 9, 10). A re-test has confirmed the result of initial test. Molecular cloning and sequencing analysis of the D13S317 locus in the proband and his daughter has failed to find allelic variants in the primer-binding region and flanking sequence, which has confirmed the novel tri-allelic pattern for the locus. Conclusion:A novel type 2 tri-allelic pattern (8, 9, 10) at the D13S317 locus has been identified among the ethnic Han Chinese population. The pattern has not been transmitted to the female offspring, and has been included in the international STRBase database for the first time.

Objective:To delineate a deletional mutation of the HLA-B gene in a Chinese pedigree.Methods:A female patient with acute myeloid leukemia who had visited Liuzhou People′s Hospital in April 2022 was selected as the study subject. Routine human leukocyte antigen (HLA) was determined by using PCR-sequence specific oligonucleotide polymorphism (PCR-SSOP) and PCR-sequence-based typing (PCR-SBT) methods. Next generation sequencing (NGS) was used to validate the candidate variant in the HLA-B gene.Results:The PCR-SBT and SSOP results for the HLA-B locus were inconsistent for the patient and her daughter. The SSOP results of the two individuals were HLA-B*35: 01, 40: 02 and HLA-B*35: 01, 40: 01, respectively. However, the PCR-SBT results has indicated a mismatch with the nearest HLA-B*35: 01 at exon 4. NGS results showed that the HLA-B*35: 01 had a 9 bp deletion in the intron 5. The patient′s husband was HLA-B*40: 01, 58: 01, which was normal. Conclusion:The variant in intron 5 of the HLA-B gene in this pedigree has mapped to a primer-binding region for the SBT reagent, which has affected the accuracy of PCR-SBT results.

Objective:To develop a genotyping method for the Junior blood type and report on a rare blood type with Jr(a-).Methods:Healthy O-type RhD+ volunteer donors of the Shenzhen Blood Center from January to May 2021 ( n=1 568) and a pedigree with difficult cross-matching ( n=3) were selected as the study subjects. Serological methods were used for proband′s blood type identification, unexpected antibody identification, and antibody titer determination. Polymerase chain reaction-sequence specific primer (PCR-SSP) method was used for typing the proband′s RHD gene. ABCG2 gene coding region sequencing and a PCR-SSP genotyping method were established for determining the genotypes of the proband and his family members and screening of Jra antigen-negative rare blood type among the 1 568 blood donors. Results:The proband′s ABO and RhD blood types were respectively determined as B and partial D (RHDDVI.3/RHD01N.01), Junior blood type Jra antigen was negative, and plasma had contained anti-D and anti-Jra. Sequencing of the ABCG2 gene revealed that the proband′s genotype was ABGG201N.01/ABGG201N.01 [homozygous c. 376C>T (p.Gln126X) variants], which is the most common Jr(a-) blood type allele in the Asian population. Screening of the voluntary blood donors has detected no Jr(a-) rare blood type. Statistical analysis of the heterozygotes suggested that the allelic frequency for ABCG2*01N.01 (c.376T) was 0.45%, and the frequency of Jr(a-) rare blood type with this molecular background was about 0.2‰. Conclusion:A very rare case of partial DVI.3 type and Jr(a-) rare blood type has been identified. And a method for identifying the Junior blood type through sequencing the coding regions of the ABCG2 gene and PCR-SSP has been established.