Gap junctions are intercellular channels which are permeable to ions and small molecules up to about 1 kDa in size. They are prominent in the skin, but their precise function there is largely unknown. Mutations in skin-expressed gap junction genes disrupt epidermal growth and differentiation. A relatively minor epidermal connexin, connexin 26 (Cx26), is associated with a wide variety of phenotypes, each specifically associated with a particular amino acid residue. How the different mutations in GJB2 lead to such distinctive phenotypes is poorly understood. Analysis of new GJB2 mutations can shed new light on pathogenesis and the apparently vital role of Cx26 in maintaining epidermal integrity.