Purine nucleoside phosphorylase deficiency
Related gene: PNP
Inheritance pattern: Autosomal recessive
Purine nucleotide phosphorylase (PNP) deficiency is a rare recessive disorder resulting in moderate to severe immunodeficiency, with reduced T cell numbers and risk of recurrent infections, as well as autoimmune disease. Autoimmune hemolytic anemia is particularly frequent in this condition. Immunoglobulin (Ig) replacement therapy and prophylactic antibiotics are warranted for treatment. Hematopoietic stem cell transplant (HSCT) can be curative for the immunologic features of PNP deficiency. Neurologic disease is also frequently described in individuals with PNP deficiency, including neurodevelopmental delay, tremors, spasticity, and ataxia.