Excretion of Orotic Acid and Orotidine in Heterozygotes of Congenital Orotic Aciduria

Abstract

A NUMBER of purine and pyrimidine bases have been demonstrated in human urine in health or in disease^1–3. Urinary excretion of orotic acid was found in studies of the propositus and so far only described case of congenital orotic aciduria⁴. Both orotic acid and orotidine (formed by the irreversible dephosphorylation of orotidine-5′-phosphate) are excreted in large amounts during therapy with 6-azauracil or 6-azauridine, compounds which on conversion to 6-azauridylic acid competitively inhibit the decarboxylation of orotidine-5′-phosphate to form uridine-5′-phosphate⁵. In work reported here evidence is presented for urinary excretion of orotic acid and orotidine by normal subjects, and for an abnormal pattern in presumed heterozygotes of congenital orotic aciduria.