Since its approval by the U.S. Food and Drug Administration (FDA) as the first immunotherapeutic agent for MM, daratumumab (Darzalex® by Janssen, Beerse, Belgium), a fully human IgG1κ monoclonal antibody (mAb) that targets CD38+ cells, has assumed a prominent role in the treatment of the disease. The gene discussed is CD38; the disease is Miyoshi myopathy.