A recent prospective, open-label, nonrandomized phase II trial reported the efficacy of abatacept even in a cohort of 10 GLILD patients with genetically undefined CVID after first-line therapy with glucocorticoids [92], basing on the previous observation that GLILD patients often exhibit increased circulating CD21low B cells expressing high levels of CD86 and decreased FOXP3+ regulatory T cells [92,93]. The gene discussed is FOXP3; the disease is common variable immunodeficiency.