Unfortunately, despite initial encouraging results from preclinical studies reporting the anti-MM activity of the selective ERα modulator 4-OH-tamoxifen [40], a feasibility clinical trial showed heterogeneous ERα expression in plasmacytosis tumor cells and the lack of activity of tamoxifen [41], thus damping the interest towards ERα as a therapeutic target in MM. The gene discussed is ESR1; the disease is Miyoshi myopathy.