Monarch Disease Ontology identifier MONDO_0009401 (hyperprolinemia type 2) is an autosomal recessive proline metabolism disorder due to pyroline-5-carboxylate dehydrogenase deficiency. The condition is often benign but clinical signs may include seizures, intellectual deficit and mild developmental delay. Also known as: 1-pyrroline-5-carboxylate dehydrogenase activity disease, ALDH4A1 hyperprolinemia, delta-1-pyrroline-5-carboxylate dehydrogenase deficiency, delta1-pyrroline-5-carboxylate dehydrogenase deficiency, disorder of 1-pyrroline-5-carboxylate dehydrogenase activity, hyperprolinemia caused by mutation in ALDH4A1.