PNP-deficiency is extremely rare. Only 33 patients with the disorder in the United States have been documented. In the United Kingdom only two children have been diagnosed with this disorder in 1994 and 2008.
Purine nucleoside phosphorylase deficiency
Dihydropyrimidine dehydrogenase deficiency
Adenine phosphoribosyltransferase deficiency
Dihydrofolate reductase deficiency
Mevalonate kinase deficiency
Guanidinoacetate methyltransferase deficiency
Methylenetetrahydrofolate reductase deficiency
Glutathione synthetase deficiency