Purine Nucleoside Phosphorylase (PNP) Deficiency: A Case Report

Abstract

Background: Purine nucleoside phosphorylase (PNP) deficiency is a rare genetic disease that results in combined immunodeficiency. Its inheritance is autosomal recessive and affects the purine metabolic pathway. There is a profound effect on T-cells and variable B-cell dysfunction. There is a strong association with neurological dysfunction in as many as two thirds of cases and autoimmunity in one third. When PNP activity is absent or greatly diminished, deoxyguanosine triphosphate (dGTP) is believed to accumulate in the mitochondria, which inhibits ribonucleotide reductase and mitochondrial DNA repair. This is very harmful to T lymphocytes and leads to DNA damage and apoptosis during thymus selection. Case: A toddler girl diagnosed with PNP) deficiency that is currently being managed using different type of modalities with good response. Results: The patient was admitted in an outside hospital when she developed fever for 4 days along with a perianal abscess. Septic shock was suspected, and she was initially started on gentamycin and tazocin then switched to vancomycin, mereponem and metrodinazole. After resolution of fever, the patient was transferred to our tertiary care center to undergo immunology work up. Upon finally receiving the patient she was stable and afebrile, however there was severe neutropenia and leukopenia. A multidisciplinary team, which included general pediatrics, hematology, Infectious diseases and immunology, handled her case. Furthermore, the patient was switched back to tazocin and gentamycin and completed 14 days with good response and full resolution of fever. Following the multidisciplinary team plan, an immunology/hematology work up was initiated. Conclusion: After 14 days of treatment, there was a good response and resolution of fever. Then, a multidisciplinary team plan, an immunology/hematology work up was initiated.