Patients typically present with excessive orotic acid in the urine, failure to thrive, developmental delay, and megaloblastic anemia which cannot be cured by administration of vitamin B12 or folic acid.

[2] Orotic aciduria is associated with megaloblastic anemia due to decreased pyrimidine synthesis, which leads to decreased nucleotide-lipid cofactors needed for erythrocyte membrane synthesis in the bone marrow.

In OTC deficiency, hyperammonemia and decreased BUN are seen because the urea cycle is not functioning properly, but megaloblastic anemia will not occur because pyrimidine synthesis is not affected.

[citation needed] Orotic aciduria can be diagnosed through genetic sequencing of the UMPS gene.

These medications will bypass the missing enzyme and provide the body with a source of pyrimidines.