Measurement of T cell receptor excision circles during newborn screening for SCID can detect some patients suffering from PNP deficiency, although removal of metabolites by maternal PNP may delay the deleterious effects on PNP-deficient lymphocytes. Few newborn screening programs also measure<unk>  metabolites in dried
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