Emanuela et al. reported that selective IgA deficiency patients have a missense mutation in one allele of TNFRSF13B (encoding transmembrane activator and calcium-modulator and cytophilin ligand interactor (TACI)), which is the receptor for tumor necrosis factor ligand superfamily, member 13b (encoding B cell activating factor belonging to the tumor necrosis factor (BAFF)) and a proliferation-inducing ligand (APRIL) [59]. Here, TNFSF13B is linked to selective IgA deficiency disease.