Although mutation analysis of SLC26A4 have been applied for diagonsis of PDS and non-syndromic hearing loss [3,10–13], SLC26A4 mutations cannot be detected in approximately one-third of patients with enlarged vestibular aqueduct (EVA), whereas only one mutant SLC26A4 allele was identified in another third [14–16]. The gene discussed is SLC26A4; the disease is hearing loss disorder.