OPA1 and myeloid sarcoma: The patients described in our case series fulfilled the revised McDonald criteria for a diagnosis of MS, with patients A and B having a primary progressive course, and patient C having a relapsing‐remitting course.19 All three patients harbored OPA1 splice site mutations: the previously described c.870+5G>A variant, and a novel c.2356‐1G>T variant that affects the canonical splice acceptor site.