CYP4F22 is a cytochrome P450 monooxygenase localized to the endoplasmic reticulum that catalyzes omega-hydroxylation of ultra-long-chain fatty acyls (C28-C36), a critical step in epidermal ceramide biosynthesis. The enzyme inserts one oxygen atom into substrate fatty acids while reducing the second oxygen to water, with electrons supplied via NADPH and cytochrome P450 reductase 1. CYP4F22 contributes to synthesis of three classes of omega-hydroxy-ultra-long chain fatty acylceramides with different sphingoid bases, all essential lipid components of the stratum corneum permeability barrier 1. Loss-of-function mutations in CYP4F22 cause autosomal recessive congenital ichthyosis (ARCI), a heterogeneous keratinization disorder characterized by generalized abnormal skin scaling 234. To date, mutations in CYP4F22 account for approximately 16% of ARCI cases 5. CYP4F22-mutated patients display relatively mild disease severity compared to mutations in other ARCI genes like TGM1 and ABCA12 5. Recent studies demonstrate that some pathogenic CYP4F22 mutations reduce protein expression but can be partially recovered by histone deacetylase inhibitors like trichostatin A, suggesting potential therapeutic approaches 6.