Purine nucleoside phosphorylase deficiency

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Purine nucleoside phosphorylase deficiency
Other namesPNP-deficiency
Purine nucleoside phosphorylase deficiency has an autosomal recessive pattern of inheritance.
TreatmentAllegeneic hemotopoietic stem cell transplantation (HSCT)

Purine nucleoside phosphorylase deficiency is a rare autosomal recessive[1] metabolic disorder which results in immunodeficiency.

Signs and symptoms

In addition to the symptoms associated with immunodeficiency, such as depletion of T-cells, decline of

mental retardation have also been reported.[citation needed
]

Cause

The disorder is caused by a mutation of the

T-cell toxicity and deficiency.[4][7] In contrast to adenosine deaminase deficiency (another deficiency of purine metabolism), there is minimal disruption to B cells.[8]

PNP deficiency is inherited in an autosomal recessive manner.

carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.[citation needed
]

Diagnosis

Diagnosis is based on the clinical examination and on laboratory findings showing leukopenia, severe lymphopenia with low CD3, CD4, and CD8 counts and variable B cell function and immunoglobulin levels. Neutropenia has also been reported. Hallmark diagnostic markers of PNP deficiency include hypouricemia, complete or near complete absence of PNP activity in red blood cell lysate and increased urine or blood levels of inosine, guanosine and their deoxy forms. Diagnosis is confirmed by genetic screening of PNP.[citation needed]

Differential diagnosis

Differential diagnosis includes aplastic anemias, SCID, severe combined immunodeficiency due to adenosine deaminase deficiency, ataxia-telangiectasia, and viral meningoencephalitis.[citation needed]

Screening

Measurement of T cell receptor excision circles during newborn screening for SCID can detect some patients with PNP deficiency, although removal of metabolites by maternal PNP may delay the deleterious effects on PNP-deficient lymphocytes. Few newborn screening programs also measure purine metabolites in dried[citation needed]

Treatment

Supportive treatment, including intravenous immunoglobulin therapy, prophylaxis for Pneumocystis carinii, and physical, occupational, and speech therapy, reduces the risk of infection and may encourage optimal neurologic development for patients.[citation needed]

Epidemiology

PNP deficiency is extremely rare. Only 33 patients with the disorder in the United States have been documented.[2] In the United Kingdom only two children have been diagnosed with this disorder in 1994 and 2008.[9]

See also

References

  1. ^
    S2CID 8373698
    .
  2. ^
    PMID 1931007
    .
  3. ^ Online Mendelian Inheritance in Man (OMIM): 164050
  4. ^
    PMID 9122228
    .
  5. ^ Motulsky A, Gartler S. "Biographical Memoirs: Eloise R. Giblett". National Academy of Sciences.
  6. ISBN 9781429229364
    .
  7. PMID 16964310
    .
  8. ^ "eMedicine - Purine Nucleoside Phosphorylase Deficiency : Article by Alan P Knutsen". Retrieved July 25, 2010.
  9. ^ "Boy first in UK with rare condition". Channel 4 News. PA News. 9 March 2009. Archived from the original on 2009-03-11.

External links

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