The tumour necrosis factor (TNF) family ligands BAFF (B-cell activating factor of TNF family) and APRIL (a proliferation-inducing ligand) are implicated in several immunological phenomena such as peripheral B-cell survival, CD40L-independent antibody production and isotype switching, autoimmunity as well as tumour cell growth [11,12]. The gene discussed is TNFSF13; the disease is Autoimmunity.