Our terminally differentiated hiPSC-derived keratinocytes from both ARCI and TTD1 patients showed different degrees of disturbed cornification, consistent with ichthyoses primary keratinocytes in vitro, proving they can mimic and be used to further elucidate the molecular pathomechanisms underlying this heterogeneous group of disorders. Here, ERCC2 is linked to autosomal recessive congenital ichthyosis.