Khan N, Kazmi Z. A Rare Case of Anti-HMGCR and Anti-SRP-Positive Immune-Mediated Necrotizing Myopathy.
Qatar Med J 2022;
2022:6. [PMID:
35261909 PMCID:
PMC8863816 DOI:
10.5339/qmj.2022.6]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022] Open
Abstract
Immune-mediated necrotizing myopathy (IMNM) or necrotizing autoimmune myopathy includes a set of distinct disorders associated with marked myasthenia, myofiber necrosis, and high creatine kinase levels. Anti-3-hydroxy-3-methylglutaryl coenzyme A reductase (anti-HMGCR) and anti-signal recognition particle (anti-SRP) are the two main autoantibodies associated with IMNM. Anti-HMGCR is usually associated with statin use. However, it may also be discovered in children without previous statin exposure, suggesting the existence of a complex genetic–environmental relationship in disease pathogenesis. Anti-SRP IMNM tends to present with more severe disease distinguished by pronounced myasthenia, worse neurologic outcomes, and treatment refractoriness. Its pathogenesis is also unknown; however, preliminary data suggest an antibody–complement-mediated mechanism of muscle cell lysis. Herein, we present the case of a 63-year-old man diagnosed with anti-HMGCR- and anti-SRP-positive IMNM that was treated with multiple immunosuppressants resulting in clinical improvement.
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