Orotic aciduria

Orotic aciduria, also called hereditary orotic aciduria, is a disease caused by an enzyme deficiency that reduces the body ability to make pyrimidines. It was the first enzyme deficiency described in the de novo pyrimidine synthesis pathway. Patients lack the enzyme UMP synthase, so they cannot convert orotic acid to UMP and excrete large amounts of orotic acid in the urine. The condition causes megaloblastic anemia and may be associated with delays in mental and physical development. It is very rare, with fewer than 30 cases reported in the medical literature across human history. The urinary excretion of orotic acid is the defining laboratory finding, and the resulting shortage of pyrimidines underlies the blood disorder.