SLC26A4 gene copy number variations in Chinese patients with non-syndromic enlarged vestibular aqueduct

Background: Many patients with enlarged vestibular aqueduct (EVA) have either only one allelic mutant of the SLC26A4 gene or lack any detectable mutation. In this study, multiplex ligation-dependent probe amplification (MLPA) was used to screen for copy number variations (CNVs) of SLC26A4 and to reveal the pathogenic mechanisms of non-syndromic EVA (NSEVA). Methods: Between January 2003 and March 2010, 923 Chinese patients (481 males, 442 females) with NSEVA were recruited. Among these, 68 patients (7.4%) were found to carry only one mutant allele of SLC26A4 and 39 patients (4.2%) lacked any detectable mutation in SLC26A4; these 107 patients without double mutant alleles were assigned to the patient group. Possible copy number variations in SLC26A4 were detected by SALSA MLPA. Results: Using GeneMapper, no significant difference was observed between the groups, as compared with the standard probe provided in the assay. The results of the capillary electrophoresis showed no significant difference between the patients and controls. Conclusion: Our results suggest that CNVs and the exon deletion in SLC26A4 are not important factors in NSEVA. However, it would be premature to conclude that CNVs have no role in EVA. Genome-wide studies to explore CNVs within non-coding regions of the SLC26A4 gene and neighboring regions are warranted, to elucidate their roles in NSEVA etiology.