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

Abstract

Objective: We aimed to evaluate the genotype-phenotype relationship in two Chinese family members with enlarged vestibular aqueduct (EVA).

Methods: 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.

Results: 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. In vitro minigene analysis confirmed that c.765+4A>G variant could cause aberrant splicing, resulting in skipping over exon 6.

Conclusions: The SLC26A4c.765+4A>G mutation is the causative variant in the Chinese family with EVA. Particular attention should be paid to intronic variants.

Keywords: SLC26A4; EVA; c.765+4A>G; splicing minigene assay.