Figure 4. Schematic drawing of K3 and K12 structure with assigned positions of the published mutations. Keratins are composed of three main parts, the central α-helical rod domain, which is divided into four subdomains (1A, 1B, 2A, and 2B), and the two non-helical variable domains (V1 and V2) at each end [3]. All three mutations within KRT3 localize exclusively in the boundary motif of the 2B subdomain. Among the mutations in KRT12, 11 were found in the 1A subdomain and six in the 2B subdomain (see also Table 2).