Given that the effects of PD-L1 on tumour physiology are mediated via intrinsic effects on the tumour cells, as well as extrinsic binding to PD-1 on effector cells, it may be useful to selectively treat high-risk MM patients according to their PD-L1 expression levels, regardless of their PD-1 status. The gene discussed is CD274; the disease is Miyoshi myopathy.