PNPLA1 and autosomal recessive congenital ichthyosis: Autosomal recessive congenital ichthyosis (ARCI) is a group of genetic diseases related to defective epidermal barriers; to date, 13 known genes have been causally associated with this disorder, namely, ALOX12B, ABCA12, ALOXE3, CERS3, CYP4F22, LIPN, NIPAL4, PNPLA1, SDR9C7, SLC27A4, SULT2B1, ST14, and TGM1 (Williams and Elias, 1985; Richard, 1993; Vahlquist et al., 2018; Simpson et al., 2020).