Defective CYP26C1 causes FFDD4

Retinoic acid (RA) is a biologically active analogue of vitamin A (retinol). RA plays an important role in regulating cell growth and differentiation. CYP26C1 is involved in the metabolic breakdown of RA by 4-hydroxylation. While CYP26C1 can hydroxylate the trans form, it is unique in hydroxylating the 9-cis isomer of RA (9cRA). Defects in CYP26C1 can cause focal facial dermal dysplasia 4 (FFDD4; MIM:614974), a rare syndrome characterised by facial lesions.

Summary from Reactome (R-HSA-5579004), read 2026-09-23.