Cellular Immune Deficiency in Two Siblings with Hereditary Orotic Aciduria

Abstract

HEREDITARY orotic aciduria is a rare inborn error of pyrimidine metabolism that is associated with autosomal recessive inheritance.¹ The disease is usually characterized by retarded growth and development, anemia, and megaloblastic bone marrow. To date, only nine patients with this disease have been described.^{2 3 4 5 6 7 8 9 10} The enzymatic defect involves either two sequential enzymes of de novo pyrimidine biosynthesis (orotate phosphoribosyltransferase [OPRT, EC 2.4.2.10.] and orotidine-5′-phosphate decarboxylase [ODC, EC 4.1.1.23.]), in the Type I form of the disease, or, as described by Fox et al.,⁸ only one of these enzymes (ODC), in the Type II form. Replacement therapy with uridine usually leads . . .