Purine nucleoside phosphorylase deficiency
Purine nucleoside phosphorylase deficiency | |
ICD-10 | D81.5 |
---|---|
ICD-9 | 277.2 |
OMIM | 164050 |
DiseasesDB | 11044 |
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Overview
Purine nucleoside phosphorylase deficiency, often called PNP-deficiency, is a rare congenital immunodeficiency of purine nucleoside phosphorylase. This enzyme is important in the purine degradation pathway. A deficiency of it causes T-cell immunodeficiency. It is also often associated with neurological disorders such as mental retardation. This autosomal recessive metabolic disorder results in severe combined immunodeficiency.
Pathophysiology
The disorder is caused by a disruption of the purine nucleoside phosphorylase, a key enzyme in the purine salvage pathway.
This enzyme is required for purine degradation. Specifically, it catalyzes the conversion of inosine and guanosine to hypoxanthine. A deficiency of it leads to build up of elevated deoxy-GTP (dGTP) levels resulting in T-cell toxicity and deficiency.[1][2]
In contrast to adenosine deaminase deficiency (another deficiency of purine metabolism), there is minimal disruption to B cells.[3]
Symptoms
In addition to the symptoms associated with immunodeficiency, such as depletion of T-cells, decline of lymphocyte activity, and an abrupt proliferation of both benign and opportunistic infections, PNP-deficiency is often characterized by the development of autoimmune disorders. Lupus-erythematosis, autoimmune hemolytic anemia, and idiopathic thrombocytopenic purpura have been reported with PNP-deficiency.[4]
Neurological symptoms, such as developmental decline, hypotonia, and mental retardation have also been reported.
Genetic prevalence
PNP-deficiency is extremely rare. Only 33 patients with the disorder in the United States have been documented.[4] In the United Kingdom only one child has been diagnosed with this disorder. [5]
References
- ↑ Snyder FF, Jenuth JP, Mably ER, Mangat RK (1997). "Point mutations at the purine nucleoside phosphorylase locus impair thymocyte differentiation in the mouse". Proc. Natl. Acad. Sci. U.S.A. 94 (6): 2522–7. doi:10.1073/pnas.94.6.2522. PMC 20121. PMID 9122228. Unknown parameter
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ignored (help) - ↑ Toro A, Grunebaum E (2006). "TAT-mediated intracellular delivery of purine nucleoside phosphorylase corrects its deficiency in mice". J. Clin. Invest. 116 (10): 2717–26. doi:10.1172/JCI25052. PMC 1560347. PMID 16964310. Unknown parameter
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ignored (help) - ↑ "eMedicine - Purine Nucleoside Phosphorylase Deficiency : Article by Alan P Knutsen".
- ↑ 4.0 4.1 Markert ML (1991). "Purine nucleoside phosphorylase deficiency". Immunodefic Rev. 3 (1): 45–81. PMID 1931007.
- ↑ http://www.channel4.com/news/articles/society/health/boy+first+in+uk+with+rare+condition/3022087
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