Consequently, some of the above-mentioned genetic defects are also found in patients diagnosed with combined immunodeficiency (CID) (e.g. mutations in ICOS, LRBA), with a CVID-like phenotype (e.g. PLCG2) (5), or with an immune dysregulation syndrome (e.g. CTLA4). The gene discussed is ICOS; the disease is combined immunodeficiency.