SLC26A4 and hearing loss disorder: However, there is evidence to show that a cohort of patients affected by hearing loss and EVA, have only one mutant allele of SCL26A4; Yang et al. showed that in patients with hearing loss and EVA, in whom thyroid disorder was not used as a clinical criterion, 19% of siblings had a single mutation in SLC26A4 and 42% had zero mutations, suggesting that other genetic factors may be involved [19] in the aetiology of their hearing loss.