Session Type: Poster Session (Monday)
Session Time: 9:00AM-11:00AM
Background/Purpose: Autoantibodies found in adult and juvenile myositis patients are often associated with specific clinical features. Prior reports have suggested that the myositis-associated autoantibody, anti-mitochondrial autoantibodies (AMA), may be associated with cardiac involvement in adults with myositis. No studies have examined the prevalence or significance of AMA in children with myositis. The purpose of this study was to define the prevalence of AMA in juvenile myositis and to investigate phenotypic differences between myositis patients with and without AMA.
Methods: We screened sera from 302 patients with juvenile dermatomyositis, 25 patients with juvenile polymyositis, and 44 patients with juvenile connective tissue disease-myositis overlap from a national myositis registry study and 92 juvenile healthy controls for AMA by ELISA, [M2 EP (MIT3) ELISA, Quanta Lite, INOVA Diagnostics, San Diego, CA]. Clinical characteristics were compared between myositis patients with and without AMA.
Results: AMA were found in 4/371 (1%) of juvenile myositis patients and 1/92 (1%) of juvenile healthy controls. Of the juvenile myositis patients, 3/4 had dermatomyositis and 1/3 had polymyositis. Onset of myositis was between 3.6 and 12.4 years of age. Two patients were positive for anti-p155/140 autoantibodies, one was positive for anti-MJ autoantibodies and one was myositis-specific autoantibody negative. All patients had muscle weakness and 3/4 patients had either Gottron’s papules or heliotrope rash. Three patients had dysphagia, 2/4 patients had calcinosis, and 2/4 patients had atypical cutaneous findings including orbital swelling and panniculitis. Overall, no distinguishing clinical features were present in the AMA positive children, and none of the AMA positive children had cardiac involvement.
Conclusion: AMA are rare in juvenile myositis and the prevalence of AMA is equivalent to that observed in healthy controls. AMA are not associated with a specific clinical phenotype in juvenile myositis.
To cite this abstract in AMA style:Sabbagh S, Pinal-Fernandez I, Casal-Dominguez M, Miller F, Mammen A, Rider L. Anti-mitochondrial Autoantibodies in Idiopathic Inflammatory Myopathies [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/anti-mitochondrial-autoantibodies-in-idiopathic-inflammatory-myopathies/. Accessed October 21, 2020.
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