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). Here, PNPLA1 is linked to Down syndrome.