GJB4 and hearing loss disorder: Gap junctional intercellular communication (GJIC) significantly contributes to normal physiology, and therefore mutations in Cx genes may cause different diseases [5] such as developmental defects (GJA1), skin diseases (GJA1, GJB2, GJB3, GJB4, and GJB6), hearing loss (GJB2, GJB3, GJB4, and GJB6), and cataracts (GJA3 and GJA8).