GJB2 and deafness: Moreover, although Cx26 KO can induce congenital deafness and hair cell degeneration (Cohen-Salmon et al., 2002; Sun et al., 2009; Wang et al., 2009), hearing loss in Cx26 KO mice occurs in advance of hair cell degeneration (Liang et al., 2012), rather than behind the cell degeneration as assumed by the K+-recycling defect hypothesis.