Analysis of genetic variants in a pedigree affected with hereditary multiple osteochondroma

Objective: To explore the genetic basis for a pedigree affected with hereditary multiple osteochondroma (HMO).

Methods: Peripheral blood samples were collected from the proband and members of his pedigree with informed consent. Following extraction of genomic DNA, all coding exons and flanking intronic sequences (-10 bp) of the EXT1 and EXT2 genes were subjected to targeted capture and next generation sequencing (NGS). Suspected variant was verified by Sanger sequencing.

Results: A heterozygous nonsense variant (c.1911C>A) was found in exon 10 of the EXT1 gene in the proband and his affected father but not in a healthy sister and normal controls. The variant was classified as a pathogenic based on the guidelines of the American College of Medical Genetics and Genomics (PVS1+PM2+PP1). Bioinformatic analysis predicted that the c.1911C>A variant may be disease-causing via nonsense-mediated mRNA decay and anomalous splicing.

Conclusions: The c.1911C>A variant probably underlay the disease in this pedigree. Discovery of this variant enriched the variant spectrum of HMO.