Follow-up of Patients With Inflammatory Myopathies Associated With a Biobank

Myositis is a rare autoimmune disease in which the immune system mistakenly attacks the patient's own peripheral muscles. This aggression manifests by muscle inflammation and necrosis responsible for a motor deficit of varying severity. The treatments available today are insufficient and are non-specific. Biological criteria, issued from simple blood or muscle tests are missing, and they will help to define the activity of the disease and the efficacy of treatments. The MASC protocol will include patients with myositis, and investigators will collect clinical, radiological, electrophysiological, histological and biological data to be used for researches aiming at better understanding this entity. A biobank (muscle biopsy, DNA, serum, plasma, PBMCs) will be acquired on this prospective cohort. The study itself will be composed of a baseline visit and monthly to yearly follow-up visits which will assess:

* Clinical examination with an evaluation of the muscle strength and function impairment/handicap, including but not limited to: * Manual testing of proximal axial and distal muscles on the five points Medical Research Council (MRC) scale * Barré tests and Mingazzini tests, number of stand-up / sitting, leg crossing * Biometry, lab and radiological measurements: muscle enzymes (creatine phosphokinase CPK, troponin, C-reactive protein, quantification of autoantibodies, muscle MRI, muscle biopsy, thorax tomodensitometry, pulmonary test function * Extra-muscular evaluation: cardiac examination and work-up (echocardiography, cardiac MRI and Positron Emission Tomography (PET) scanner, cardiac biopsies), pulmonary evaluation, rheumatological and dermatological assessment, history of thromboembolic disease and cancer Patient activity assessment: evaluation of daily life activity by both patient and physician using a Visual Analogue Scale * Quality of life questionnaires * Evaluation of the efficacy and toxicity of specific treatments For each patient, the date of last visit or contact will be collected as well as outcomes, particularly for the cause of death if relevant. Data from the biobank MASC " Muscles DNA/RNA Serum and Cells " will be added to other data. The biobank has been fully registered with local authorities and ethical committees ("Committee for Personal Protection (CPP)" CPP agreement). It contains peripheral blood mononuclear cells (PBMC), serum, DNA and RNA from blood and muscular biopsies collected at the diagnosis stage. The database contains immunological and genetical data.

This prospective study will also aim at:

* Identify the differential pathophysiological processes between the different subgroups of myositis * Identify prognostic factors, including the different treatment modalities used * Improve physiopathological knowledge (clinico-anatomobiological characteristics and identification of other biomarkers through the biobank) * Improve the evaluation of the clinical outcomes/endpoints for future trials * Develop clinical trials for homogeneous subgroups of patients, based on their pathophysiology and evaluated on the appropriate endpoints.

• Characterisation of the natural history of myositis subgroups :responses to treatments, prognosis factors, evolution [Time frame: up to twenty years after inclusion]
• Characterisation of an immune system signature, using peripheral blood mononuclear cells and muscular biopsies, DNA and RNA sequencing, and autoantibodies [Time frame: baseline: first 30 days after inclusion]
• Risk factors for All-cause mortality depending on patient's and disease characteristics [Time frame: up to twenty years after inclusion]
• Change of the quality of life, using quality of life questionnaires, depending of patients and disease characteristics [Time frame: up to twenty years after inclusion]
• Change of activity impairment using an evaluation of daily life activity by both patient and physician using a Visual Analogue Scale depending of patients and disease characteristics [Time frame: up to twenty years after inclusion]
• Characterisation of a quality-of-life scale using biological data (CPK), muscle weakness (muscle testing) and other visceral involvements [Time frame: up to twenty years after inclusion]
• Characterisation of a global activity scale using biological data (CPK), muscle weakness (muscle testing) and other visceral involvements [Time frame: up to twenty years after inclusion]
• Incidence of major cardio-vascular events [Time frame: up to twenty years after inclusion]
• Consequences on outcomes of major cardio-vascular events [Time frame: up to twenty years after inclusion]
• Correlation of myositis with the development of extra-muscular diseases including but not limited to dermatological, rheumatological, cardiological and pneumological associated diseases [Time frame: up to twenty years after inclusion]
• Characterisation of respiratory function with pulmonary function test and thoracic tomodensitometry [Time frame: up to twenty years after inclusion]
• Characterisation of respiratory function with pulmonary function test and thoracic tomodensitometry [Time frame: up to twenty years after inclusion]