A novel splicing mutation in SMPX is linked to nonsyndromic progressive hearing loss.

OBJECTIVE: X-linked nonsyndromic hearing impairment is the rarest form of genetic hearing loss and represents only a minor fraction of all cases. The aim of this study was to investigate the cause of X-linked nonsyndromic sensorineural hearing loss in a three-generation American family.

METHODS: Whole-exome sequencing and co-segregation analysis were used to identify disease-causing genes.

RESULTS: In this study, we described in detail the clinical characteristics of the family and identified a novel frameshift mutation creating a premature stop codon (c.133-1 G > A, p.(Gly45fs*36)) of SMPX. The loss-of-function mutation was co-segregated with the progressive hearing loss phenotype and was absent in 200 normal controls.

CONCLUSIONS: We report the first SMPX (DFNX4) mutation in a North American family. Our findings contribute to the existing genotypic and phenotypic spectrum of SMPX associated hearing loss. Furthermore, our data suggest that exome sequencing is promising in the genetic diagnosis of hearing loss.