A novel SLC26A4 splicing mutation identified in two deaf Chinese twin sisters with enlarged vestibular aqueducts.

Background Variants in theSLC26A4gene are correlated with nonsyndromic hearing loss with an enlarged vestibular aqueduct (EVA). This study aimed to identify the genetic causes in a Chinese family with EVA, and the pathogenicity of the detected variants. Methods We collected blood samples and clinical data from a pair of deaf twin sisters with EVA and their family members. As controls, a group of 500 normal-hearing people were enrolled in our study. Twenty-one exons and flanking splice sites of theSLC26A4gene were screened for pathogenic mutations by polymerase chain reaction and bidirectional Sanger sequencing. Minigene assays were used to verify whether the novelSLC26A4intronic mutation influenced the normal splicing of mRNA. Results Hearing loss in the twins with EVA was diagnosed using auditory tests and imaging examinations. Two pathogenic mutations, c.919-2A>G and c.1614+5G>A were detected in SLC26A4, the latter of which has not been reported in the literature. The minigene expressionin vitroconfirmed that c.1614+5G>A could cause aberrant splicing, resulting in skipping over exon 14. Conclusions On the SLC26A4 gene, c.1614+5G>A is a pathogenic mutation. This finding enriches the mutational spectrum of theSLC26A4gene and provides a basis for the genetic diagnosis of EVA.