Steps where genetic mutations are linked to ichthyoses are illustrated. Mutations in either ALOX12B or ALOXE3 result in nonbullous congenital ichthyosiform erythroderma (NCIE), also referred to as type 5 lamellar ichthyosis. We speculate that CYP4F22 could modulate hepoxilin/trioxilin bioactivity in type 3 lamellar ichthyosis as indicated. (The omega position is highlighted in each case, suggesting a role for CYP4F22.)