Anti-Hmgcr Antibodies As Specific Marker for Immune Mediated Necrotizing Myopathies

http://acrabstracts.org/abstract/anti-hmgcr-antibodies-as-specific-marker-for-immune-mediated-necrotizing-myopathies/Background/Purpose : Autoantibodies are important biomarkers in the diagnosis of idiopathic inflammatory myopathies (IIM) including polymyositis (PM) and dermatomyositis (DM), inclusion body myositis (IBM) as well as overlap syndromes. Recently, it was reported that the prevalence of necrosis in patients with IIM is increasing and that the majority of the patients with necrosis exhibit autoantibodies to 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the molecular target of statins. This is the first international multi-center study on anti-HMGCR antibodies in a large cohort of patients. Methods: A total of 1906 samples from IIM patients and controls were collected at 12 different sites from nine different countries. Among patients with IIM (n=1250), 69 had immune mediated necrotizing myopathies (IMNM), 406 had PM, 525 had DM, 10 had PM/Scleroderma overlap syndrome, 45 had juvenile dermatomyositis (JDM), 18 had myositis overlap syndromes (MOS), 53 had amyopathic dermatomyositis (ADM), 49 had antisynthetase syndrome (ASS), 64 had cancer-associated myositis and 11 had IBM. All samples were tested for anti-HMGCR antibodies by ELISA. Results: Anti-HMGCR antibodies were present in 44.9% of IMNM, 4.4% of PM, 1.9% of DM, 6.7% of JDM, in 1.2% of primary Sjögren`s syndrome (pSS) and in 0.4% of systemic lupus erythematosus patients (see Table 1). Conclusion: Anti-HMCGR antibodies characterize a subpopulation of IMNM patients previously exposed to statin and were significantly associated with an older age. However, it is important to note that not all patients with those autoantibodies had a history of exposure to statins indicating that different phenotypes and mechanisms exist.status: publishe