A 4 year old girl presented to hospital with failure to thrive. Her peripheral blood smear showed megaloblastic anemia. Vitamin B12 & folate were given but anemia did not improve. Enzyme assay from the cultured PBMC showed deficiency of OP (Orotate Phospho Ribosyl Transferase). What could be the probable diagnosis ?
High-Yield Explanation
Orotic aciduria Due to deficiency of orotate phosphoribosyl transferase and OMP decarboxylase Leads to defect in DNA Synthesis Characterizedby : Excretion of orotic acid in urine, Severe anemia Megaloblastic Not improved with folate /vitamin B12/vitamin C Retarded growth Rx- Feeding diet rich in uridine / cytidine