Defects in IP3R3, caused by mutations in ITPR3 identified in patients with immunodeficiency, were found to impair Ca2+ signaling after T-cell receptor (TCR) stimulation (Neumann et al., 2023), as presented by Julika Neumann (KU Leuven, Leuven, Belgium). Here, ITPR3 is linked to Immunodeficiency.