GJB2 and keratitis: We have found that 4 of 9 mutations (A88V, N14K, N14Y, and A40V) that cause keratitis ichthyosis deafness syndrome abolish CO2 sensitivity of Cx26 gap junctions and hemichannels in a transdominant manner (Meigh et al., 2014; de Wolf et al., 2016; Cook et al., 2019; Nijjar et al., 2021).