Two mutated copies of the SLC26A4 gene are associated with Pendred syndrome, comprised of bilateral hearing loss with enlargement of the vestibular aqueduct (EVA) and thyroid goiter.  Other EVA patients have a normal thyroid gland and only one mutated copy of SLC26A4.  Our study identified the same combination, or haplotype, of noncoding sequence variants upstream of the non-mutated copy of SLC26A4 in most of these nonsydromic EVA patients.  This haplotype defines the most common allele associated with hereditary hearing loss in Caucasians.  Testing for this haplotype will facilitate the genetic and prognostic counseling of many patients with EVA. (By Dr. Andrew J Griffith, http://jmg.bmj.com/content/early/2017/08/05/jmedgenet-2017-104721 )

(Source: https://www.nidcd.nih.gov/health/enlarged-vestibular-aqueducts-and-childhood-hearing-loss )