Purine Nucleoside Phosphorylase Deficiency: A Case Report of an Extremely Rare Disorder.

Purine nucleoside phosphorylase (PNP) deficiency is one of the very rare types of immune deficiency disorders inherited in an autosomal recessive (AR) manner. PNP deficiency is a progressive immune disorder that can range from severe combined immunodeficiency (SCID) to combined immunodeficiency and is associated with recurrent infections, neurological manifestations, and sometimes autoimmune disorders. In our case, we describe the case of a female patient, two years and six months old, with recurrent infections, severe neutropenia, failure to thrive, and a history of a deceased sister with the same condition. She was diagnosed with PNP through genetic testing, which confirmed the homozygous variant c.46T>C p.(Trp16Arg) in PNP, in addition to clinical manifestations and the positive history of her sister.