<prompt> Deficiency of purine nucleoside phosphorylase causes -Complement deficiencyCellular immunodeficiencyHumoral immunodeficiencyCombined immunodeficiency  <response>: Ans. is b i.e., Cellular immunodeficiency o Purine nucleoside phosphorvlase is involved in purine nucleoside catabolism.o Purine nucleoside phosphorylase PNP deficiency is an autosomal recessive disorder,o It is characterized by decreased cell mediated immunity and recurrent infection,o There is a severe T-cell deficiency with normal B-cel! function.o They usually present with hypoplastic anemia with recurrent pneumonia, diarrhea and candidiasis.Also knowo Adenosine deaminase deficiency causes severe combined immunodeficiency. 