Our current study directly demonstrates that individuals with this SLC26A4 genotype-haplotype result are unlikely to develop the thyroid abnormality and increased severity of hearing loss associated with Pendred syndrome and mutations affecting the splice sites or coding regions of both alleles of SLC26A4. Finally, this study indicates that CEVA may act as a genetic modifier to increase the severity of hearing loss in ears with EVA caused by factors other than mutations affecting the coding regions or splice sites of SLC26A4. Here, SLC26A4 is linked to Pendred syndrome.