[MIM*239500 & MIM*239510] A metabolic disorder characterized by enhanced plasma proline concentrations and urinary excretion of proline, hydroxyproline, and glycine; autosomal recessive inheritance. Type I hyperprolinemia is associated with a deficiency of proline oxidase and renal disease; type II hyperprolinemia is associated with a deficiency of pyrroline-5-carboxylate dehydrogenase, mental retardation, and convulsions and is caused by mutation in the pyrroline 5 carboxylate gene (P5CD) on 1p.