IMiD drugs such as lenalidomide are commonly used to treat MM, where they are often combined with proteasome inhibitors.8, 9 There are several hypothesized mechanisms of action for IMiDs, including CRBN‐mediated ubiquitin proteasome‐mediated degradation of IKZF1/IKZF347 leading to loss of IRF4,48 among other pro‐survival factors. Here, CRBN is linked to Miyoshi myopathy.