CYP46A1 deficiency is reported in the brains of HD patients and mice [36, 37, 39] In addition, the cholesterol catabolite 24-OHC is decreased in the brain and the plasma from HD mice, post-mortem tissue and plasma from HD patients [23, 29, 31, 36, 37, 40, 41]. Here, CYP46A1 is linked to Huntington disease.