Recurrence of CCHS-associated PHOX2B Poly-Alanine expansion variant due to paternal mosaicism.

BACKGROUND: Paired-like Homeobox 2B (PHOX2B) is considered the causative gene of Congenital Central Hypoventilation Syndrome (CCHS), a dominant genetic disorder characterized by impaired central respiratory control and subsequent hypoventilation during sleep. METHODS: Herein, we present a family with recurrent severe CCHS. The potential causative genetic variant was confirmed through Whole-Exome Sequencing (WES), Sanger sequencing, and droplet digital PCR (ddPCR). Furthermore, prenatal diagnosis was performed on the proband's mother at 20 weeks of her fourth pregnancy upon request. RESULTS: The proband and her brother were both carriers of the PHOX2B polyalanine expansion variant: c.744_758dupCGCGGCAGCGGCGGCGGCGGC. Sanger sequencing revealed that the proband's father had a small variant peak in the gene position, implying potential somatic mosaicism. In addition, ddPCR results showed that the proband's father had germline mosaicism, with a mosaicism proportion of 14.3%. Notably, the detect p.(Ala241[26]) variant was not detected in the fetus. CONCLUSIONS: These findings have important implications for improving genetic counseling of CCHS families as they suggest that even parents without CCHS symptoms may have somatic chimerism, necessitating careful genetic counseling and consideration of prenatal testing for subsequent pregnancies.

Integrated analysis of microRNA and mRNA expression profiles in Preeclampsia.

BACKGROUND: Preeclampsia (PE), a pregnancy specific syndrome, is one kind of common gestational hypertension disease, which can cause maternal and perinatal mortality and morbidity. This study was conducted to identify key microRNAs (miRNAs), mRNAs and related signaling pathways in the pathogenesis of PE. METHODS: Whole transcriptome sequencing and small RNA sequencing of the peripheral blood from 3 PE patients and 3 normal pregnant women were performed. Differential expressed (DE) miRNAs were identified using the DEseq2 package. Target genes of the selected upregulated and downregulated DE miRNAs were predicted. Based on the hypergeometric distribution of DE miRNA target genes, we analyzed GO enrichment and KEGG pathway enrichment using R. RESULTS: Total 1291 and 1281 novel RNAs were obtained from the preeclampsia patients and healthy individuals. 70 miRNAs were screened out with significant levels with 51 significantly upregulated and 19 significantly downregulated. 44,306 genes were predicted as the targets of these miRNAs. Besides, KEGG pathway analysis revealed that the upregulated miRNAs were enriched in Glycosaminoglycan biosynthesis-chondroitin sulfate / dermatan sulfate, Base excision repair and the downregulated miRNAs were enriched in Tuberculosis, Phagosome. CONCLUSION: We constructed regulatory networks of miRNAs and target genes, there were 2208 negative miRNA-mRNA interactions in total. The network and pathway information illustrate the potential functions of mRNAs and miRNAs in PE pathogenesis.

[Carrier screening and prenatal diagnosis for thalassemia-associated mutations in Jiaxing area of Zhejiang].

OBJECTIVE: To study the molecular epidemiology of thalassemia in Jiaxing area of Zhejiang province and provide a basis for prenatal diagnosis, genetic counseling and prevention and control of birth defects. METHODS: A total of 24 003 pregnant women who presented at the Jiaxing Maternal and Child Health Care Hospital from April 2017 to September 2021 were enrolled. Capillary hemoglobin electrophoresis in combination with routine blood test were used for primary screening for carriers of thalassemia-associated mutations, and those with positive results were subjected to fluorescence quantitative PCR assay. Prenatal diagnosis was provided for couples with a risk of giving birth to children with intermediate or severe thalassemia. RESULTS: Among the 24 003 pregnant women, 1 211 cases were suspected as carriers of thalassemia-associated mutations, among whom 443 (36.58%) were confirmed by genetic testing. Among these, carriers of α-, ß- and α-complex ß-globin gene mutations have accounted for 27.31% (121/443), 70.65% (313/443) and 2.04% (9/443), respectively. The result of prenatal diagnosis for an at-risk couple was --SEA/αCSα, and the fetus was predicted to have intermediate or severe thalassemia. Termination of the pregnancy was recommended. CONCLUSION: Hemoglobin electrophoresis combined with routine blood test during pregnancy may be used as a preliminary screening measure for carriers of thalassemia-associated variants. Combined with genetic testing, this will be of great significance for the control of thalassemia in this region.

NPFFR2 gene compound heterozygous variants associated with preeclampsia identified by whole-exome sequencing.

BACKGROUND: Preeclampsia (PE) is an idiopathic disorder of pregnancy. The exact cause of PE remains unknown. Emerging evidence indicates that the cause of PE is linked to genetic factors. Therefore, the aim of this study was to identify the susceptibility genes for PE. METHODS: Nine families with severe PE were recruited. The whole-exome sequencing (WES) was performed on each family, and Sanger sequencing was used to identify the potential pathogenic genetic variants. RESULTS: After a rigorous bioinformatics analysis, compound heterozygous variants in the NPFFR2 gene, NM_004885.2: c.601A > G, p.Met201Val and c.995C > T, p.Ala332Val were found in the No.4 pedigree. Bioinformatics analysis showed that these sites were highly conserved among several species and were predicted to be pathogenic variants according to multiple online mutational function prediction software packages. Due to the compound heterozygous variants of NPFFR2, more bonds are generated between mutant amino acids and spatial adjacent amino acids, which may lead to more stable active conformation of protein and not easy to be degraded. CONCLUSIONS: We demonstrated for the first time that compound heterozygous variants of the NPFFR2 gene might be potentially associated with severe PE, the results of this study provide clinicians and researchers with a better understanding of the molecular mechanisms underlying severe PE in pregnant women.

Identification and comparison of circular RNAs in preeclampsia.

BACKGROUND: Preeclampsia (PE) is a pregnancy-specific syndrome, belongs to the gestational hypertension diseases category and is considered among the causes of maternal and perinatal mortality and morbidity. However, the pathogenesis of PE is still vague. METHODS: In the present study, the circular RNA (circRNA) expression patterns of normal pregnant women and PE patients were investigated using whole RNA sequencing. RESULTS: A total of 151 differential expressed circRNAs were identified including 121 upregulated and 30 downregulated ones. Functional and pathway enrichment analysis was conducted on the differentially expressed circRNAs using Gene Ontology and KEGG databases. The results of this analysis indicated that several crucial biological processes and pathways were enriched in PE patients. circRNA-microRNA (miRNA) interaction analysis indicated that the reported differentially expresse circRNAs may be associated with some regulatory functions through miRNAs in PE patients. Two ceRNAs networks were constructed according to the targeting relationship between circRNAs/miRNAs and miRNAs/mRNAs. One sub-network contained one upregulated circRNA, four downregulated miRNAs and five upregulated mRNAs, and another sub-network contained 10 downregulated circRNAs, 21 upregulated miRNAs and 15 downregulated mRNAs. CONCLUSION: CircRNA expression patterns have been investigated and this analysis revealed their potential regulatory mechanisms in PE patients. We constructed the ceRNAs (competing endogenous RNA) to reveal the potential molecular roles of dysregulated circRNAs in the PE patients using RNA sequencing data. circRNA_13301 was the only one upregulated circRNA in ceRNA being targeted by four miRNAs.

A Beckwith-Wiedemann syndrome case with de novo 24 Mb duplication of chromosome 11p15.5p14.3.

BACKGROUND: Molecular genetic testing for the 11p15-associated imprinting disorder Beckwith-Wiedemann syndrome (BWS) is challenging because of the molecular heterogeneity and complexity of the affected imprinted regions. An integrated molecular approach to analyze the epigenetic-genetic alterations is required for accurate diagnosis of BWS. CASE PRESENTATION: We reported a Chinese case with BWS detected by SNP array analysis and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA). The genetic analysis showed a de novo duplication of 24 Mb at 11p15.5p14.3 is much longer than ever reported. MS-MLPA showed copy number changes with a peak height ratio value of 1.5 (three copies) at 11p15. The duplication of paternal origin with increase of methylation index of 0.68 at H19 and decreased methylation index of 0.37 at KCNQ1OT1. CONCLUSION: Combined chromosome microarray analysis and methylation profiling provided reliable diagnosis for this paternally derived duplication of BWS. The phenotype associated with 11p15 duplications depends on the size, genetic content, parental inheritance and imprinting status. Identification of these rare duplications is crucial for genetic counselling.

[Prenatal diagnosis of a tetrasomy 18p case using BACs-on-Beads technology and single nucleotide polymorphism array].

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.

KRT9 gene mutation as a reliable indicator in the prenatal molecular diagnosis of epidermolytic palmoplantar keratoderma.

Epidermolytic palmoplantar keratoderma (EPPK) is the most frequent form of such keratodermas. It is inherited in an autosomal dominant pattern and is clinically characterized by diffuse yellowish thickening of the skin on the palms and soles with erythematous borders during the first weeks or months after birth. EPPK is generally caused by mutations of the KRT9 gene. More than 26 KRT9 gene mutations responsible for EPPK have been described (Human Intermediate Filament Database, www.interfil.org), and many of these variants are located within the highly-conserved coil 1A region of the α-helical rod domain of keratin 9. Unfortunately, there is no satisfactory treatment for EPPK. Thus, prenatal molecular diagnosis or pre-pregnancy diagnosis is crucial and benefits those affected who seek healthy descendants. In the present study, we performed amniotic fluid-DNA-based prenatal testing for three at-risk pregnant EPPK women from three unrelated southern Chinese families who carried the KRT9 missense mutations p.Arg163Trp and p.Arg163Gln, and successfully helped two families to bear normal daughters. We suggest that before the successful application of preimplantation genetic diagnosis (PGD), and noninvasive prenatal diagnosis of EPPK that analyzes fetal cells or cell-free DNA in maternal blood, prenatal genetic diagnosis by amniocentesis or chorionic villus sampling (CVS) offers a quite acceptable option for EPPK couples-at-risk to avoid the birth of affected offspring, especially in low- and middle-income countries.

Genetic diagnosis of autosomal dominant polycystic kidney disease by targeted capture and next-generation sequencing: utility and limitations.

Mutation-based molecular diagnostics of autosomal dominant polycystic kidney disease (ADPKD) is complicated by genetic and allelic heterogeneity, large multi-exon genes, and duplication sequences of PKD1. Recently, targeted resequencing by pooling long-range polymerase chain reaction (LR-PCR) amplicons has been used in the identification of mutations in ADPKD. Despite its high sensitivity, specificity and accuracy, LR-PCR is still complicated. We performed whole-exome sequencing on two unrelated typical Chinese ADPKD probands and evaluated the effectiveness of this approach compared with Sanger sequencing. Meanwhile, we performed targeted gene and next-generation sequencing (targeted DNA-HiSeq) on 8 individuals (1 patient from one family, 5 patients and 2 normal individuals from another family). Both whole-exome sequencing and targeted DNA-HiSeq confirmed c.11364delC (p.H3788QfsX37) within the unduplicated region of PKD1 in one proband; in the other family, targeted DNA-HiSeq identified a small insertion, c.401_402insG (p.V134VfsX79), in PKD2. These methods do not overcome the screening complexity of homology. However, the true positives of variants confirmed by targeted gene and next-generation sequencing were 69.4%, 50% and 100% without a false positive in the whole coding region and the duplicated and unduplicated regions, which indicated that the screening accuracy of PKD1 and PKD2 can be largely improved by using a greater sequencing depth and elaborate design of the capture probe.

RET proto-oncogene genetic screening of families with multiple endocrine neoplasia type 2 optimizes diagnostic and clinical management in China.

BACKGROUND: Genetic screening for germline mutations in the RET proto-oncogene has been extensively exploited worldwide to optimize the diagnostic and clinical management of multiple endocrine neoplasia type 2 (MEN2) patients and their relatives. However, a distinct lag period exists not only in the recognition but also in the medical treatment of patients with MEN2. Here we present a comprehensive genetic and clinical analysis of MEN2 among Chinese families followed from 1975 to 2011. Our series comprises 36 index cases and 134 relatives from 11 independent families. METHODS: Genetic diagnosis was performed in all participants by direct sequencing all relevant RET exons. Thyroidectomy was performed in 50 patients with varying cervical neck dissection procedures. Patients with pheochromocytoma (PHEO) underwent specific surgery. Demographic, clinical profiles, mutation types, tumor histopathologic features, and follow-up records were systematically analyzed. RESULTS: The RET mutations p.C634Y (n=34), p.C634R (n=6), p.C618S (n=13), p.V292M/R67H/R982C (n=7), p.L790F (n=2), and p.C634Y/V292M/R67H/R982C (n=1) were confirmed in 31 index cases and then identified in 32 at-risk relatives (mutation carriers), with MEN2A as the most common clinical subtype. The overall penetrance of PHEO in patients with MEN2A was 46.7%. A total of 50 patients underwent thyroidectomy, and there was a significant lowering of their mean age at thyroidectomy and the tumor diameter of the mutation carriers that were detected and operated on compared with the index cases (age at first surgery: 29.3 vs. 39.3 years, p<0.05; maximum size: 1.1 vs. 3.3 cm, p<0.001). There was also a decrease in the TNM staging and the proportion of patients who underwent inappropriate initial thyroid surgery (pN1: 31.6% vs. 100%, p<0.001; inappropriate surgery: 0% vs. 29%). Meanwhile, disease-free survival (DFS) increased (DFS: 100% vs. 58.1%, p<0.05). Both medullary thyroid carcinoma-specific (n=1) and PHEO-specific (n=5) deaths were reported during the study period. CONCLUSIONS: Our results further substantiate that gene scanning of all relevant RET exons is a powerful tool in the management of MEN2 patients, especially in asymptomatic carriers, and has led to earlier diagnosis and more complete initial treatment of patients with MEN2 in China.