The fact that, in individuals with ACOX2 deficiency, abnormal liver function tests can improve with ursodeoxycholic acid treatment, which does not reduce synthesis of C27 bile acids, indicates clearly that treatment of the different peroxisomal disorders needs to be assessed as individual disorders; not all cases of trihydroxycholestanoic acidaemia are the same. The gene discussed is ACOX2; the disease is peroxisomal disease.