A subset of MM cases (25 of 59, 42%) exhibited an immune cell infiltrate that resembled the BM microenvironment of healthy mice, while a subset of cases (34 of 59, 58%) was characterized by more abundant lymphoid cells, primarily CD8+ T lymphocytes with exhausted phenotypes (Fig. 4d and Extended Data Fig. 4d). Here, CD8A is linked to Miyoshi myopathy.