ASL and guanidinoacetate methyltransferase deficiency: Coene et al. [9] correctly identified 42 out of 46 diagnoses and could not diagnose argininosuccinate lyase deficiency, dimethylglycine dehydrogenase deficiency and GAMT deficiency, because abnormal values of argininosuccinic acid, dimethylglycine and guanidinoacetic acid were not annotated.