Monarch Disease Ontology id MONDO_0009612 (methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency) can be described as follows. Vitamin B12-unresponsive methylmalonic acidemia is an inborn error of vitamin B12 (cobalamin) metabolism characterized by recurrent ketoacidotic crises or transient vomiting, dehydration, hypotonia and intellectual deficit, which does not respond to administration of vitamin B12. There are two types of vitamin B12-unresponsive methylmalonic acidemia: mut0 and mut-. Also known as: methylmalonic acidemia due to methylmalonyl-CoA mutase deficiency, methylmalonic aciduria mut type, methylmalonyl-CoA mutase deficiency, methylmalonyl-Coenzyme A mutase deficiency, vitamin B12-unresponsive methylmalonic aciduria.