Novel mutations and hot-spots in patients with purine nucleoside phosphorylase deficiency.

Purine nucleoside phosphorylase (PNP) deficiency results in severe immune dysfunction and early death from infections. Lymphopenia, reduced serum uric acid, and abnormal PNP enzymatic activity assist in the diagnosis of PNP-deficient patients. Analysis of the gene encoding PNP in these patients reveals several recurring mutations. Identification of these hot-spots for mutation may allow faster confirmation of the diagnosis in suspected cases.