Analysis of serum revealed that both 26-HC and 3β-hydroxycholest-5-en-(25R)26-oic acid (3β-HCA), two metabolites derived from the oxidation of cholesterol by the enzyme cytochrome P450 27A1 (CYP27A1, cytochrome P450 family 27 subfamily A member 1), were reduced in the ALS patient group, suggesting dysregulation, or a reduced activity, of this enzyme is associated with ALS [32]. This evidence concerns the gene CYP27A1 and amyotrophic lateral sclerosis.