Clinical and genetic analysis of a Chinese pedigree affected with Smith-Lemli-Opitz syndrome

Abstract

To explore the clinical phenotype and pathogenic variants in a Chinese pedigree affected with Smith-Lemli-Opitz syndrome. Peripheral blood samples were collected from five members, including two affected ones, from the pedigree for the extraction of genomic DNA. Whole exome sequencing was carried out, and candidate variants were verified by Sanger sequencing as well as reverse transcription sequencing at the RNA level. The proband and another affected child from the pedigree showed mental retardation, dyskinesia, microcephaly, micrognathia, anteverted nares, and 2/3 toe syndactyly. The proband also had hypospadia, single upper incisor, and lower serum cholesterol level. Both children were found to harbor a paternally derived c.278C>T (p.T93M) variant and a maternally derived c.907G>A (p.G303R) variant of the DHCR7 gene. Both were known pathogenic mutations. The compound heterozygous mutations of c.278C>T (p.T93M) and c.907G>A (p.G303R) of the DHCR7 gene probably underlay the disease in this pedigree. Above finding has enabled early diagnosis and treatment of Smith-Lemli-Opitz syndrome.