However, there is evidence that low-grade MC—in particular MC affecting the lymphoid lineage (CD3+/CD4+)—is associated with lower non-relapse mortality (NRM): in line with previous reports, Baron et al. showed that lymphoid MC is associated with a lower rate of grade 2–4 acute graft-versus-host disease (GVHD) in patients who underwent RIC (9, 16, 17). The gene discussed is CD4; the disease is acute graft versus host disease.