Loss-of-function (LOF) mutations in ACOX1 cause a rare and severe autosomal recessive disorder known as peroxisomal acyl-CoA oxidase deficiency or pseudoneonatal adrenoleukodystrophy (P-NALD) (OMIM #264470), characterised by VLCFA accumulation [98]. This evidence concerns the gene ACOX1 and peroxisomal acyl-CoA oxidase deficiency.