The signaling lymphocytic activation molecule family (SLAMF) of surface proteins is comprised of nine members, four of which are highly expressed on plasma cells from MM patients regardless of disease stage: SLAMF2 (CD48), SLAMF3 (CD229; Ly9), SLAMF6 (CD352), and SLAMF7 (CS1 or CD319). The gene discussed is LY9; the disease is Miyoshi myopathy.