الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
T
he idiopathic inflammatory myopathies are characterized by muscle weakness, skin disease and internal organ involvement. Autoimmunity is known to have a role in myositis pathogenesis, and myositis-specific autoantibodies, targeting important intracellular proteins, are regarded as key biomarkers aiding in the diagnosis of patients (Betteridge et al., 2015).
Autoimmune myopathies can present with diverse phenotypes and extra muscular systems affection, our aim is the illustration of different clinical pictures, Magnetic resonance findings and laboratory data in relation to myositis auto antibodies in a cohort of Egyptian patients.
We conducted this descriptive observational study in Ain Shams university hospital over a period of 2 years from March 2020 to March 2022, a total of 77 patients were recruited and 10 control samples were collected.
Samples were tested for Mi-2alpha, Mi-2beta, TIF1gamma, MDA5, NXP2, SAE1, Ku, PM-Scl100, PM-Scl75, Jo-1, SRP, PL-7, PL-12, EJ, OJ, Ro52 antibodies using the EUROLINE autoimmune inflammatory myopathy immunoblotting antigens kit and Anti HMGCR CoA antibody titer using the QUANTA Lite® HMGCR ELISA kit.
A total of 34 patients tested positive for Myositis Auto-antibodies,11 of which had juvenile onset of the disease symptoms, they showed female sex predominance (61.7%), the mean values for their age and age of onset were 28.618±14.346 and 23.574±13.584 respectively, 13 samples tested positive for immune mediated necrotizing myopathy (IMNM) auto antibodies, 12 samples were positive for antibodies associated with dermatomyositis, Antibodies associated with overlap syndrome were found in 12 samples and 7 samples had antibodies for anti-synthetase syndrome.
18 patients of our studied sample tested positive for Myositis specific autoantibodies, 8 had positive Myositis associated autoantibodies while the remaining 8 tested positive for both.
The highest percentage was types associated with connective tissue disorders (17 patients), followed by Immune medicated necrotizing myopathy subtype (8 patients) followed by anti-synthetase syndrome antibodies (3 patients) while 6 patients tested positive for multiple antibodies. 11 of the positive samples had juvenile onset of symptoms among which 5 patients had antibodies associated with overlap syndrome and dermatomyositis, 3 had IMNM antibodies, one had anti-synthetase syndrome antibodies while 2 tested positive for multiple antibodies.
Anti SRP and Anti PM-Scl antibodies were the most frequent in the juvenile group while in adults Anti HMGCR was positive in approximately 26% of the 23 positive adult-onset samples.
We conclude that testing for serum autoantibodies aids greatly in the diagnosis and classification of myositis patients into different categories with distinct clinical features and associations for each category, this in combination with radiological and other laboratory findings can result in a more accurate and rapid diagnosis and plan of management.