Osteoarthritis (OA) is the most common type of arthritis, affecting more than two million older people in the UK, causing pain and stiffness as the cartilage at the ends of bones wears away. It can affect any joints but involvement of the knee and hip is the number one cause of mobility problems in the elderly population. Despite its high prevalence there is no effective drug treatment to control the progression of osteoarthritis, and currently available painkillers carry a high risk of side effects. The aim of the arcOGEN study is to identify the genetic changes, known as polymorphisms, that increase the risk of people developing OA. The charity expects that this could lead to several potential breakthroughs such as genetic tests becoming available to predict who is likely to develop OA, particularly at a young age, and how severely. Ultimately it could lead to new drugs that could slow down disease progression and even prevent OA occurring. The two year study will be funded by a grant of £2.2m - the largest single grant ever awarded by arc. All the major OA genetics research groups within the UK and experts in human genetics will be involved in this study. arcOGEN could be the most important study the charity has ever funded and could have far-reaching consequences in terms of better understanding of the disease and identifying new treatment targets. Genetics experts in London, Manchester, Southampton, Nottingham, Edinburgh, Newcastle, Oxford and Cambridge will form part of the UK-wide collaborative project. The arcOGEN team hope to find between ten and 20 of the genes that could have a strong to moderate risk for osteoarthritis, although there may be many more. It may become possible for medics to perform a genetic-risk profile alongside a lifestyle-risk profile to determine the overall risk, and then offer treatment or advice on how the risk could be reduced. The consortium’s investigation of the DNA of 8,000 patients would provide it with “unprecedented power.” The results would be made freely available as an international resource that could be mined for insights into new treatments.