Monoallelic mutations in NFKB1 causing genetic or functional NF-κB1 haploinsufficiency have recently been reported to not only account for CVID-like B-cell deficiency, but a rather complex immunodeficiency-like profile including the emergence of combined B- and T-cell dysfunction (5–13). The gene discussed is NFKB1; the disease is common variable immunodeficiency.