In order to understand the genetic aspects / causes of myositis, and ultimately develop more effective treatment therapies, it will be necessary to collect blood samples and clinical details from around 1000 patients with myositis. As the condition is very rare, it will not be possible to get the required number of patients from one centre alone, and therefore, a collaborative, multicentred approach will be needed. Consultant rheumatologists and neurologists throughout the UK, who have patients with PM, DM or IBM, will be approached, and asked if they would like to officially enter into the myositis genomic multicentred study. Once ethical and R&D approval has been granted, consultants will be named as the 'Principal Investigators' at each of these 'research sites' and could then start to recruit suitable patients into the study.