Complex sentence: Purine nucleoside phosphorylase deficiency, often called PNP-deficiency, is a very rare autosomal recessive metabolic disorder which results in severe combined immunodeficiency due to a disruption of the purine nucleoside phosphorylase enzymatic pathway.
Split into simpler sentences: Purine nucleoside phosphorylase deficiency, often called PNP-deficiency, is a very rare autosomal recessive metabolic disorder which results in severe combined immunodeficiency. It is to a disruption of the purine nucleoside phosphorylase enzymatic pathway.