A 7-Month-Old Boy Is Evaluated in the Clinic for Recurrent

Multiple Choice

A 7-month-old boy is evaluated in the clinic for recurrent bacterial infections. His tonsils are not visible on physical examination. Serum immunoglobulin A (IgA) and IgG levels are markedly decreased, and serum IgM levels are slightly below normal. Based on this family's history and clinical presentation, a mutation in which of the following genes is most likely to be found in this patient?

A) JAK3 kinase
B) Adenosine deaminase
C) Common cytokine receptor ƴ chain
D) RAG2
E) Purine nucleoside phosphorylase