Mutations in ABC transporters have been reported in several other genetic skin diseases, including ABCA12 in lamellar ichthyosis type 2 as well as the severe and lethal ichthyosis, Harlequin ichthyosis, ABCC9 in Cantú syndrome, and ABCC6 in the connective tissue disorder pseudoxanthoma elasticum (PXE) [41] – [46]. This evidence concerns the gene ABCC9 and autosomal recessive congenital ichthyosis 4A.