SLC26A4 and hearing loss disorder: Mutations in the SLC26A4 gene are probably the second most common cause of inherited hearing loss, after GJB2 mutations, and are responsible for Pendred syndrome as well as DFNB4 (non-syndromic hearing loss with inner ear abnormalities, such as enlarged vestibular aqueduct (EVA) with or without Mondini dysplasia (MD)) [5,6].