For instance, a variant located in the TNFSF13B gene, regulating the levels of B cells in the general population, was also a disease-predisposing variant for multiple sclerosis and systemic lupus erythematosus (SLE), its mechanism of action was characterized, thereby the role of B cells in the diseases was clarified [5]. The gene discussed is TNFSF13B; the disease is systemic lupus erythematosus.