GJB2 and autosomal recessive nonsyndromic hearing loss 1A: The most common form of hereditary nonsyndromic hearing loss is autosomal recessive deafness 1A (DFNB1A, MIM#220290) caused by pathogenic variants in the GJB2, GJB6, and GJB3 genes encoding connexin 26 (Cx26), connexin 30 (Cx30), and connexin 31 (Cx31) proteins, respectively.