Variants in theGap Junction Protein Beta 2 gene (GJB2, HGNC: 4284), which encodes a beta-2 gap junction protein (connexin 26; Cx26), have been shown to be the leading genetic cause of NSHL.GJB2-related autosomal recessive deafness explains approximately50% of congenital autosomal recessive deafness, andGJB2-related autosomal dominant deafness is extremely rare. The gene discussed is GJB2; the disease is hearing loss, autosomal recessive.