To investigate the potential correlation between the expression of JAG1 and JAG2 and the extent of tumor cell burden in MM patients, we leveraged a set of 34 BMBs obtained from MM patients at disease onset, previously analyzed via immunohistochemistry to identify the presence of monoclonal light chains, JAG ligands, and HES6 [21]. The gene discussed is JAG1; the disease is Miyoshi myopathy.