MONDO_0013171 (purine nucleoside phosphorylase deficiency) can be described as follows. Purine nucleoside phosphorylase (PNP) deficiency is a disorder of purine metabolism characterized by progressive immunodeficiency leading to recurrent and opportunistic infections, autoimmunity and malignancy as well as neurologic manifestations. Also known as: PNP deficiency, PNPase deficiency, deficiency of inosine phosphorylase, immunodeficiency due to purine nucleoside phosphorylase deficiency, purine-nucleoside phosphorylase deficiency.