Protein expression assays increased the spectrum of the diagnoses achieved and helped reach definitive diagnosis in several disorders like, DOCK8 deficiency, LRBA deficiency, XLA, CGD, Perforin deficiency, ADA deficiency, IL7RA deficiency, LADI and MHC-II deficiency [12, 21, 22, 27]. The gene discussed is DOCK8; the disease is hyperinsulinemic hypoglycemia, familial, 4.