An anomaly of bile acid synthesis characterized by mild cholestatic liver disease, fat malabsorption and/or neurological disease. The disease is congenital bile acid synthesis defect 4 (Monarch Disease Ontology term MONDO_0008967). Also known as: 2-methylacyl-CoA racemase deficiency, Alpha-methyl-acyl-CoA racemase deficiency, BAS defect type 4, BASD4, CBAS4, bile acid synthesis defect, congenital, type 4, congenital bile acid synthesis defect type 4, intrahepatic cholestasis with defective conversion of trihydroxycoprostanic acid to cholic acid.