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

Abstract

To explore the genetic etiology of a Chinese pedigree featuring non-simplex blepharocheilodontic syndrome. 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. 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. 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.