Mutations that inactivate the ALOX12B gene product are associated with autosomal recessive congenital ichthyosis (ARCI) types including harlequin ichthyosis, lamellar ichthyosis and congenital ichthyosiform erythroderma.39 These rare diseases are characterized by epidermal scaling and birth as collodion babies.40 After loss of the collodion membrane in the first weeks of life these patients exhibit generalized scaling, erythema, epidermal hyperplasia and hyperkeratosis. This evidence concerns the gene ALOX12B and Harlequin ichthyosis.