GJB6 and hearing loss disorder: p.Trp77Ser (non-polar-to-polar variant) in transmembrane domain 2 of the membrane protein Connexin 30.2/Connexin 31.4 (CX30.2/CX31.3) causes hearing loss, possibly by introducing structural instability and promoting mutant CX30.2/CX31.3 aggregation in the endoplasmic reticulum [36].