The bone marrow biopsy showed a small-cell IgM MM with an increased number of CD138+, CD79a+, free monoclonal κ-light chain restricted, IgM+, cyclin D1+, CD31+, CD45−/+, CD20−, EMA−, CD56− plasma cells (65–70%) (Figs. 1a–d, 2a). The gene discussed is CD40LG; the disease is Miyoshi myopathy.