Southampton medic in world’s first major genome screen for osteoarthritis

A Doctor at the University of Southampton is to be involved in the world’s first search of the human genome for genetic risk factors for osteoarthritis.

On World Arthritis Day (October 12) the Arthritis Research Campaign (arc) has announced plans to run a definitive genome-wide association study of osteoarthritis susceptibility called arcOGEN; the largest study of its kind ever undertaken. The study will involve screening the DNA of 8,000 people suffering from osteoarthritis of the hip and knee and 6,000 healthy people to compare the differences.

Dr Nigel Arden, reader and consultant rheumatologist at the MRC Epidemiology Resource Centre at the University of Southampton, is one of several genetic experts who is part of the UK-wide consortium, and will be recruiting more than 650 osteoarthritis patients from clinics at Southampton General Hospital to take part in the study.

The aim of the arcOGEN study is to identify the genetic changes, known as polymorphisms, that increase the risk of people developing osteoarthritis. The charity expects that this could lead to several potential breakthroughs such as genetic tests becoming available to predict who is likely to develop osteoarthritis, particularly at a young age, and how severely. Ultimately it could lead to new drugs that could slow down disease progression and even prevent osteoarthritis occurring.

The two-year study will be funded by a grant of £2.2m - the largest single grant ever awarded by the medical research charity.

"Patients who suffer from osteoarthritis of the hip and knee experience marked pain which often disrupts their daily activities and quality of life", said Dr Arden. "Currently there is no cure, but we hope that this project may help us to identify the genetic causes of osteoarthritis and ultimately help to develop new treatments."

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.

Wrongly thought of as an inevitable consequence of ageing, osteoarthritis is a disease in its own right but the reasons why some people do, and some do not develop the disorder are unclear.

"Osteoarthritis is an extremely debilitating disease characterised by joint pain and reduced mobility, and is the biggest cause of disability in older people bar none", explained Dr John Loughlin, principal investigator of the arcOGEN study, and a geneticist from the Nuffield Department for Orthopaedic Surgery at the University of Oxford.

"Genetic factors play a major role in the development of OA and identifying them will help us to understand why the disease occurs and will assist in the development of new treatments by identifying new molecular targets. We have brought together all the major OA genetics research groups within the UK and experts in human genetics to enable us to perform the definitive search of the human genome for OA genetic risk factors", added Dr Loughlin.

Professor Alan Silman, medical director of the Arthritis Research Campaign said that arcOGEN could be the most important study the charity had ever funded and could have far-reaching consequences in terms of better understanding of the disease and identifying new treatment targets.

"Compared with many other conditions where scientists have looked for a genetic basis, there is a very strong belief that OA is genetically-based because there are many families which have OA running through the generations", he said. "Until now we didn’t know what that genetic basis was, but now we have the modern technology we have a unique opportunity to unlock the genetic code."

It is known that there is a considerable genetic component to osteoarthritis, and those people with a parent or sibling with the condition are two to three times more likely to develop OA than those who don’t. However, there are also other risk factors such as obesity, a sports injury or a heavy manual occupation. 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.

Dr Loughlin said that 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. The outcome of the genome screen is likely to be of considerable interest to pharmaceutical companies wanting to develop new drugs to prevent the onset of osteoarthritis. Identifying predisposing genes will point out new biological pathways to target.

The arcOGEN team hopes 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. Human DNA contains about 30,000 genes, with millions of polymorphisms, which will all be checked by sampling patients’ DNA taken from their white blood cells.

Genetics experts in London, Manchester, Newcastle, Oxford, Edinburgh, Cambridge and Nottingham will also form part of the UK-wide collaborative project.