A novel intronic variant causing aberrant splicing identified in two deaf Chinese siblings with enlarged vestibular aqueducts.

Abstract

We aimed to evaluate the genotype-phenotype relationship in two Chinese family members with enlarged vestibular aqueduct (EVA). We collected blood samples and clinical data from each pedigree family member. Genomic DNA was isolated from peripheral leukocytes using standard methods. Targeted next-generation sequencing and Sanger sequencing were performed to find the pathogenic mutation in this family. Minigene assays were used to verify whether the novel intronic mutation SLC26A4c.765+4A>G influenced mRNA splicing. Hearing loss in the patients with EVA was diagnosed using auditory tests and imaging examinations. Two pathogenic mutations, c.765+4A>G and c.919-2A>G were detected in SLC26A4. Invitro minigene analysis confirmed that c.765+4A>G variant could cause aberrant splicing, resulting in skipping over exon 6. The SLC26A4c.765+4A>G mutation is the causative variant in the Chinese family with EVA. Particular attention should be paid to intronic variants.