PRODH and deafness: They result from a deficiency in PRODH and P5 enzymes in type I and type II hyperprolinemias, and plasma proline concentrations range from 500 to 1,000 μmol/L and 1,500 to 3,000 μmol/L, respectively.14, 15, 16 These conditions are associated with congenital renal anomalies, deafness, and neurological disorders, but not with tubular injuries resulting from high proline concentration.14