Orotic aciduria is a rare autosomal recessive inborn error of pyrimidine metabolism resulting from mutations in the UMPS gene. This gene codes for the enzyme orotate phosphoribosyltransferase (OPRT), which plays a key role in the catabolism of uridine monophosphate (UMP). Deficiency of this enzyme leads to the accumulation and excessive excretion of orotic acid in the urine. If left untreated,...