The acyl-CoA synthetase long-chain family member 4 gene (ACSL4, also known as FACL4) encodes an enzyme that catalyzes the addition of coenzyme A to long-chain fatty acids, with high preference for arachidonic acid. However, the exact function of ACSL4 in the brain is currently unknown. ACSL4 is located on Xq22.3 and contains 14 coding exons. Missense and splicing mutations have been reported in patients with X-linked mental retardation (Melonie I et al. Nat Genet. 2002;30:436-440).