Gene Summary: PNP gene encodes an enzyme which reversibly catalyzes the phosphorolysis of purine nucleosides. The enzyme is trimeric, containing three identical subunits. Mutations which result in nucleoside phosphorylase deficiency result in defective T-cell (cell-mediated) immunity but can also affect B-cell immunity and antibody responses. Neurologic disorders may also be apparent in patients with immune defects. A known polymorphism at aa position 51 that does not affect enzyme activity has been described. A pseudogene has been identified on chromosome 2. [provided by RefSeq, Jul 2008]General information above from NCBI
Tissue specificity: Expressed in red blood cells; overexpressed in red blood cells (cytoplasm) of patients with hereditary non- spherocytic hemolytic anemia of unknown etiology.
Involvement in disease: Purine nucleoside phosphorylase deficiency (PNPD) [MIM:613179]: A disorder that interrupts both the catabolism of inosine into hypoxanthine and guanosine into guanine, and leads to the accumulation of guanosine, inosine, and their deoxified by- products. The main clinical presentation is recurrent infections due to severe T-cell immunodeficiency. Some patients also have neurologic impairment. Note=The disease is caused by mutations affecting the gene represented in this entry.
Sequence similarity: Belongs to the PNP/MTAP phosphorylase family.