A novel mutation in the SMPX gene associated with X-linked nonsyndromic sensorineural hearing loss in a Chinese family.

X-linked inheritance is very rare and is estimated to account for only 1-5% of all nonsyndromic hearing loss cases. We found a multiplex family from China segregating with X-linked nonsyndromic hearing loss. After exclusive analysis of 10 common variations of three hearing loss-related genes, GJB2, mtDNA12srRNA and SLC26A4, a novel truncated variant of SMPX, c.87dupA (p.Gly30Argfs*12) (NCBI ClinVar Submission ID: SUB3136126), was identified by whole-exome sequencing. This variant was co-segregated with hearing loss in the entire family and was absent in 576 unrelated ethnically and geographically matched controls. We also detected a single nucleotide variation in two male controls with normal hearing, SMPX c.55A>G (p.Asn19Asp), which has been annotated as a rare variant in the Single Nucleotide Polymorphism (dbSNP) (rs759552778) and Exome Aggregation Consortium (ExAC) databases. This study has enriched the mutation spectrum of the SMPX gene.