PNPLA1 and autosomal recessive congenital ichthyosis: We found several of the genes causing ARCI and other forms of ichthyosis to be induced during keratinocyte differentiation, i.e., TGM1, ALOXE3, ALOX12B, NIPAL4, CYP4F22, ABCA12, ABHD5, PNPLA1, ELOVL4, LIPN and CERS3 (see Table 2).