Clinical Significance
PNPase together with adenosine deaminase (ADA), serves a key role in purine catabolism, referred to as the salvage pathway. Mutations in ADA lead to an accumulation of (d)ATP, which inhibits ribonucleotide reductase, leading to a deficiency in (d)CTPs and (d)TTPs, which, in turn, induces apoptosis in T-lymphocytes and B-lymphocytes, leading to severe combined immunodeficiency (SCID).
PNP-deficient patients will have an immunodeficiency problem. It affects only T-cells; B-cells are unaffected by the deficiency.
Read more about this topic: Purine Nucleoside Phosphorylase
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