PNPLA1 and autosomal recessive congenital ichthyosis: Many of the genes induced by differentiation are also known to be mutated in autosomal recessive congenital ichthyosis (ARCI) or syndromes with congenital ichthyosis, i.e., TGM1, ALOX12B, ALOXE3, CYP4F22, NIPAL4, ABCA12, PNPLA1, CERS3, ABHD5, ALDH3A2, ELOVL4 and SPINK5 (Table 2).