GJB2 and hearing loss disorder: Numerous functional studies have been performed to better understand the role of pathogenic GJB2 variants in the TM2 of Cx26 associated with non-syndromic recessive hearing loss (located at positions Arg77, Ile82, Val84, 86Thr, Ala88, and Leu90); however, the obtained results are sometimes inconsistent [116,117,118,119,121,124,136,152,163,164,165,166].