In our study, all patients with ALPS, lipopolysaccharide-responsive and beige-like anchor protein (LRBA) deficiency and immune dysfunction, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome developed autoantibodies, highlighting the role of B-cell homeostasis (Fas deficiency), Treg (IPEX syndrome) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) surface expression (LRBA deficiency) in the control of autoreactive B cells and autoantibody production. Here, CTLA4 is linked to autoimmune lymphoproliferative syndrome.