MRCP-0240

A 11-year-old boy is referred to you following his seventh course of antibiotics in the last six years for lower respiratory tract infections. He also has a history of eczema for which he is currently on a topical steroid cream. His full blood count (FBC) report shows: Hb: 13.9 g/dL, Plts: 65 x 10^9/L, WCC: 12.3 x 10^9/L. Which of the following genes should you expect an abnormality in?