[Analysis of clinical features and genetic variant in a child with Cowden syndrome 1].

OBJECTIVE: To explore the genetic etiology of a child with Cowden syndrome 1 (CS1). METHODS: A child who had visited the Ningbo Women and Children's Hospital on August 26, 2022 was selected as the study subject. Clinical information of the child was collected. Genomic DNA was extracted from peripheral blood samples of the child and his family members and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RESULTS: The child, a 13-year-old boy, had manifested with severe mental retardation, hyperactivity, autistic behavior, sparse and prominent teeth, macrocephaly, and skin freckles on the penis. His mother had presented with multiple papules, hamartomatous polyps, thyroid adenoma and macrocephaly. WES results revealed that the child has harbored a nonsense c.781C>T (p.Q261*) variant of the PTEN gene, which was inherited from his mother. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.781C>T variant was classified as likely pathogenic (PVS1+PM2_Supporting). CONCLUSION: The c.781C>T variant of the PTEN gene probably underlay the pathogenesis in the child and his mother. Above finding has facilitated genetic counseling for this family.

Report of new variants in PPIL1 underlying type 14 pontocerebellar hypoplasia and their associated phenotypic manifestations in two fetuses.

Mutations in the PPIL1 gene have been linked to type 14 pontocerebellar hypoplasia (PCH14); however, prenatal clinical characteristics of PCH14 caused by mutations in the PPIL1 gene have not been reported. This study reports the first prenatal case of PCH14 diagnosed by whole-exome sequencing (WES). Two fetuses with severe microcephaly and cerebral dysplasia, along with their parents, underwent WES. The effects of the discovered PPIL1 variants on PPIL1 protein function were investigated using bioinformatics tools. WES revealed two compound heterozygous missense mutations in PPIL1, c.376C > G (p.His126Asp) and c.392G > T (p.Arg131Leu), inherited from the mother and father, respectively. The co-segregation of PPIL1 mutations in this family was confirmed using Sanger sequencing, identifying two PCH14-affected fetuses. Bioinformatics analysis revealed that these mutations could disrupt the formation of hydrogen bonds, altering the structural stability of the PPIL1 protein. This study is the first to define the clinical characteristics of PCH14 during pregnancy and reports a novel heterozygous missense variant, expanding the PCH14-related mutational spectrum of PPIL1.

[Genetic analysis of a Chinese pedigree featuring non-simplex blepharocheilodontic syndrome].

OBJECTIVE: To explore the genetic etiology of a Chinese pedigree featuring non-simplex blepharocheilodontic syndrome. METHODS: Whole exome sequencing was carried out to detect genetic variant and copy number variations (CNVs) in the pedigree. Suspected variants were verified by Sanger sequencing and qPCR. RESULTS: The fetus and its elder brother, father and grandfather were found to harbor a heterozygous c.83delG (p.A29Rfs*55) variant of the CTNND1 gene, which was unreported previously. In addition, its elder brother was also found to be a double heterozygote for a c.235delC (p.L79Cfs*3) variant of GJB2 gene and a c.538C>T (p.R180X) variant of GJB3 gene, which were respectively inherited from his mother and father. CNVs analysis revealed a de novo heterozygotic deletion (1.46 Mb) at 17q12 in the mother, which was confirmed by qPCR. Based on American College of Medical Genetics and Genomics guidelines, the c.83delG variant, the c.235delC variant and the 17q12 microdeletion were predicted as pathogenic, while the c.538C>T variant was of uncertain significance. CONCLUSION: The c.83delG (p.A29Rfs*55) variant of the CTNND1 gene probably underlay the pathogenesis of non-simplex blepharocheilodontic syndrome in this pedigree. The double heterozygous variants of c.235delC (p.L79Cfs*3) of GJB2 gene and c.538C>T (p.R180X) of GJB3 gene probably underlay the hearing loss in the elder brother. The bilateral renal cysts in the mother may be attributed to the 17q12 microdeletion. Above results have provided guidance for genetic counseling and prenatal diagnosis for this pedigree.