Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Purine nucleoside phosphorylase deficiency
Introduction
Synonyms and keywords: PNP-deficiency
Overview
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.
Historical Perspective
Historical Perspective
Classification
Classification
Pathophysiology
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]
Causes
Causes
Differentiating Purine nucleoside phosphorylase deficiency from Other Diseases
Differentiating Purine nucleoside phosphorylase deficiency from Other Diseases
Epidemiology and Demographics
Epidemiology and Demographics
Prevalence
File:Autorecessive.svg 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.
Risk Factors
Risk Factors
Screening
Screening
Natural History, Complications, and Prognosis
Natural History, Complications, and Prognosis
Natural History
Complications
Prognosis
Diagnosis
Diagnosis
Diagnostic Criteria
History and 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.
Physical Examination
Laboratory Findings
Imaging Findings
Other Diagnostic Studies
Treatment
Treatment
Medical Therapy
Surgery
Prevention
References
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
|month=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
|month=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.
Template:Purine, pyrimidine, porphyrin, bilirubin metabolic pathology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]