defect in alpha methylacyl-CoA racemase

Alpha methylacyl-CoA racemase (AMACR) deficiency is a recently described defect in bile acid side-chain oxidation. This peroxisomal enzyme catalyzes the conversion of (25R) trihydroxy-cholestanoic acid (THCA) to its 25S isomer, a step that is essential for the subsequent peroxisomal β-oxidation to primary bile acids to be initiated. High concentrations of (25R) THCA are found in the urine, bile and serum of these patients.