Research carried out by the University of Manchester has identified further genes that can lead to rheumatoid arthritis and could also explain why three times more women than men suffer from the condition.
It is believed that both environmental and genetic factors determine whether a person will suffer from rheumatoid arthritis, which affects more than 400,000 people in the UK.
The latest study was carried out by a team of scientists at the Arthritis Research UK Epidemiology Unit at the University of Manchester and was published in the journal Nature Genetics. The research used advanced technology and a large collection of international samples. It revealed 14 new genes and also identified genes that are specific to the female X-chromosome. A further 32 other genes had already been identified and the team believes that it has now discovered the vast majority of the genes that cause the disease.
Dr Stephen Eyre who compiled the report said: "This work will have a great impact on the clinical treatment of arthritis; we have already found three genes that are targets for drugs, leaving a further 43 genes with the potential for drug development, helping the third of patients who fail to respond well to current medications.
"Although patients who first present at clinic have similar symptoms, it is likely that their route to developing disease has involved a varied path. The genetic findings can help divide patients into smaller groups with more similar types of rheumatoid arthritis and assist in the allocation of therapies and disease management."
Professor Jane Worthington, study lead based at the NIHR Manchester Musculoskeletal Biomedical Research Unit, said: "This groundbreaking study brought together scientists from around the world and involved the use of DNA samples from more than 27,000 patients with rheumatoid arthritis and healthy controls. As a result of our findings, we now know that genetic variations at over 45 regions of the genome determine susceptibility to this form of arthritis.
"We observed remarkable similarities with genetic markers associated with other autoimmune diseases. Our future work will focus on understanding how the simple genetic changes alter normal biological processes and lead to disease. Ultimately, this will help us to develop novel therapies and improved targeting of existing drugs."
Professor Alan Silman, medical director of Arthritis Research UK, said: "This large genetics study has added a significant amount to the current knowledge of the genetic basis of rheumatoid arthritis. We hope that this research will lead to a greater understanding of the disease and allow us to develop targeted drug treatments for the half-a-million people currently living with rheumatoid arthritis.
"This is the first time that a genetic association has been established between rheumatoid arthritis and the X chromosome. This could provide a useful clue in helping us to understand why rheumatoid arthritis is three times more likely to occur in women."