Prenatal whole-exome sequencing for fetal structural anomalies: a retrospective analysis of 145 Chinese cases.

BACKGROUND: Whole-exome sequencing (WES) significantly improves the diagnosis of the etiology of fetal structural anomalies. This study aims to evaluate the diagnostic value of prenatal WES and to investigate the pathogenic variants in structurally abnormal fetuses. METHODS: We recruited 144 fetuses with structural anomalies between 14 and 2020 and 15 December 2021 in the study. Genetic screening was performed by WES combined with karyotyping and chromosomal microarray analysis. The molecular diagnostic yield of prenatal WES for each type of fetal structural anomaly and the identified pathogenic genes and mutations were reported. RESULTS: In this study, we retrospectively analyzed the clinical and genetic data of 145 structurally anomalous fetuses. These cases were classified into 9 phenotypic classes based on antenatal ultrasound findings. Thirty-eight pathogenic variants in 24 genes were identified in 35 of the 145 cases, including 14 novel variants in 13 genes (EP300, MYH3, TSC2, MMP9, CPLANE1, INVS, COL1A1, EYA1, TTC21B, MKS1, COL11A2, PDHA1 and L1CAM). Five additional pathogenic variants were classified as incidental findings. Our study showed that the overall diagnosis rate of WES was 28.1% (27/96) in the parent-fetus trio cases and 16.3% (8/49) in the proband-only cases. Fetuses with musculoskeletal anomalies had the highest diagnostic yield (51.4%, 19/37). In addition, FGFR3 and COL1A1 were the most common pathogenic genes. CONCLUSIONS: Our work expands the mutation spectrum of the genes associated with fetal structural anomalies and provides valuable information for future parental genetic counselling and pregnancy management of the structurally anomalous fetuses.

Identification of a novel 10.3 kb deletion causing α0-thalassemia by third-generation sequencing: Pedigree analysis and genetic diagnosis.

BACKGROUND: α-thalassemia is an inherited blood disorder caused by variants in the α-globin gene cluster. Identification of the pathogenic α-globin gene variants is important for the diagnosis and management of thalassemia. METHODS: Two suspected families from Xiantao, Hubei Province were recruited in this study. The family members underwent hemoglobin testing. Polymerase Chain Reaction based reverse dot blot (PCR-RDB) was employed to identify the known variants. Next-generation sequencing (NGS) and third-generation sequencing (TGS) were performed to screen the potential disease-causing variants, which were validated by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA). RESULTS: Hematological analysis suggested that proband A had α-thalassemia traits, and proband B had HbH disease traits. However, only a -α3.7 mutation had been detected by PCR-RDB and NGS in the proband of family B. Subsequent TGS identified a novel 10.3 kb deletion (NC_000016.10:g.172342-182690del) covering the HBA1, HBQ1 and HBA2 genes in the α-globin gene cluster in both family A and B, which was confirmed by Sanger sequencing and MLPA. These results indicated that the novel deletion is likely responsible for α-thalassemia. CONCLUSION: A novel α-thalassemia deletion was identified for the two families by TGS. Our work broadened the molecular spectrum of α-thalassemia, and was beneficial for the diagnosis, genetic counseling and management of α-thalassemia.

Perinatal outcomes of prenatal cases testing positive for trisomy 9 by noninvasive prenatal testing.

OBJECTIVES: To evaluate the performance of non-invasive prenatal testing (NIPT) for the detection of fetal trisomy 9 in prenatal screening and to investigate the prenatal appearances and genetic counseling of trisomy 9 fetuses. MATERIALS AND METHODS: The ultrasonography information, laboratory detection and pregnancy outcome of 16 cases of single pregnancy with trisomy 9 identified by NIPT who received amniocentesis in our prenatal diagnosis center from January 2018 to December 2020 were retrospectively analyzed. RESULTS: Among the 16 cases, 2 cases of trisomy 9, 3 cases of trisomy 9 mosaicism, 2 cases reporting of regions of homozygosity and 9 cases of false positive were diagnosed. Among the true positive cases, 4 cases showed abnormal ultrasonic finding: 3 cases terminated pregnancy and 1 case was lost to follow-up. Another 1 case was in utero fetal demise in the second trimester without structural abnormality, and 2 cases were normal live birth without developmental abnormalities. In the 9 cases with normal kayrotyping, 1 case had termination of pregnancy and 1 case with mental retardation and poor cognitive ability, other 7 had good pregnancy outcomes. CONCLUSION: Our results may be helpful for the selection of prenatal diagnostic strategies and genetic counseling for pregnant women with trisomy 9 revealed by NIPT.

The prevalence and outcomes of α- and ß-thalassemia among pregnant women in Hubei Province, Central China: An observational study.

ABSTRACT: There is no information concerning the prevalence of thalassemia among pregnant women in Hubei Province currently. This study is aimed to explore the prevalence of α- and ß-thalassemia genotypes among pregnant women in Hubei Province, and to explore the clinically applicable screening approach, as well as to investigate the pregnancy outcomes of α- and ß-thalassemia carriers.Pregnant participants were recruited from 4 hospitals for the screening of α- and ß-thalassemia mutations in Hubei Province. Polymerase Chain Reaction and flow cytometry methods were used to examine α- and ß-thalassemia mutations. The hematological parameters and pregnancy outcomes of α- and ß-thalassemia carriers were obtained from the hospital information system. The chi-square tests were used to evaluate the difference in hematological parameters between pregnant thalassemia carriers and the control group.Among 11,875 participants, 414 (3.49%) were confirmed with α-thalassemia carriers, 228 (1.92%) were confirmed with ß-thalassemia carriers, and 3 (0.03%) were confirmed with both α- and ß-thalassemia carriers. The frequency of -α3.7 accounted for 2.05% and it was the most frequent genotype of α-thalassemia; the proportion of IVS-II-654 was 0.85% and it was the most frequent genotype of ß-thalassemia in Hubei Province. Furthermore, the proportion of patients with low mean corpuscular volume (MCV) or mean cell hemoglobin (MCH) values was accounted for 36.64% and 93.97% among α-thalassemia and ß-thalassemia carriers, respectively. And participants with normal MCV and MCH values were accounted for 95.07% among non-thalassemia participants. High prevalence of pregnancy-induced diabetes (16.97%), preterm birth (9.96%), pregnancy-induced hypertension (8.12%), and low birth weight (5.90%) were observed among pregnant thalassemia carriers.MCV and MCH values were suggested to apply on the preliminary screening of pregnant ß-thalassemia; however, it's unpractical on that of α-thalassemia. Furthermore, thalassemia carriers might have a high risk of negative pregnancy outcomes. These findings could be useful for the preliminary screening of thalassemia and perinatal care for the pregnant thalassemia carriers.

[Genetic Mutation Characteristics of Glucose-6-Phosphate Dehydrogenase Deficiency Patients in Wuhan].

OBJECTIVE: To explore the genotype mutation characteristics of patients with glucose-6-phosphate dehydrogenase(G6PD) deficiency in Wuhan. METHODS: A total of 1 321 neonates with positive screening and outpatients were received G6PD mutation detection, 12 kinds of common G6PD mutation in Chinese people was detected by using multicolor melting curve analysis (MMCA) method, for those with negative results, the enzyme activity and clinical information were analyzed, sequencing was recommended after informed consent when it is necessary. RESULTS: Among 1321 patients, a total of 768 mutations were detected out, with a detection rate of 58.1%. A total of 18 types of G6PD genotypes were identified, including c.1388G>A, c.1376G>T, c.95G>A, c.1024C>T, c.871G>A, c.392G>T, c.487G>A, c.1360C>T, c.1004C>A, c.517T>C, c.592C>T, c.94C>G, c.152C>T, c.320A>G, c.1028A>G, c.1316G>A, c.1327G>C and c.1376G>C, including 683 male hemizygotes, 3 female homozygotes, 80 female heterozygotes and 2 female compound heterozygous. CONCLUSION: A total of 18 types of G6PD mutations are identified in the reaserch, and c.94C>G, c.1028A>G and c.1327G>C are first reported in Chinese population. The most common G6PD mutation types in Wuhan are c.1388G>A, c.1376G>T, c.95G>A.