Case 22–2019: A 65-Year-Old Woman with Myopathy

To the Editor:

We would like to expand on the discussion by Freeman et al. on statin-associated autoimmune myopathy with autoantibodies against HMGCR in a patient who had been prescribed a statin medication. First, we would note that this disease may also be associated with a dietary source of statins, such as red yeast rice or oyster mushrooms.¹ Second, since at least 25% of patients with anti-HMGCR–associated autoimmune myopathy have no known exposure to statins,² testing for anti-HMGCR autoantibodies may be considered in other patients with myopathy. This includes adults and children with clinical presentations that are consistent with genetic muscle disease but no known genetic defect; some of these patients have anti-HMGCR–associated autoimmune myopathy that responds to treatment.³ Third, reinitiation of statins is contraindicated in patients with statin-associated autoimmune myopathy. However, the use of proprotein convertase subtilisin–kexin type 9 (PCSK9) inhibitors appears to be safe in this patient population and may be considered in patients with clinically significant cardiovascular risk factors.⁴