There are no obvious differences in the results of the present cell-based ω-hydroxylase assay between missense and truncating mutations in CYP4F22. Thus, whether causative mutations are missense or truncating might not be a definitive factor for the SHCB phenotype in patients with ARCI from CYP4F22 mutations. Here, CYP4F22 is linked to autosomal recessive congenital ichthyosis.