The genetic deficiency of CR4 is associated with recurrent bacterial infections, and patients die during childhood unless they receive allogenic bone marrow transplantation (92). It is common in patients with primary immunodeficiency, with leukocyte adhesion deficiency type 1 (LAD1), lacking four integrins, including CR3 and CR4 (114). The gene discussed is CRIPTOP4; the disease is hyperinsulinemic hypoglycemia, familial, 4.