16 January 2010
Appeared in BioNews 541An international consortium composed of research groups in America, England and Australia has published its work in January's edition of the Nature Genetics journal, identifying six genetic regions associated with the autoimmune sidease ankylosing spondylitis (AS).
AS is a chronic arthritic condition, which is thought to be affecting 2.4 million people in the US alone. It is a systemic autoimmune disease meaning that the body's own immune system starts to attack itself, in turn causing an overactive inflammatory response, which can then cause joints to swell and become painful. AS attacks the spine specifically and has an early age onset with many patients experiencing back pain in their teenage years. Over time the spine stiffens and can end up becoming fixed, resulting in the patient being hunched over in a forward position, unable to bend or move freely. Little is known about the causes of AS and the current treatment options of painkillers, physiotherapy and expensive antibody therapy only address the symptoms.
The groups in Texas, Oxford and Queensland completed a genome-wide association scan of over 2000 people with more than 5000 matched controls. They found six genetic regions to be linked to AS with two in particular showing strong correlation; ANTXR2 and IL1R2, which are both known to be involved in regulating inflammatory processes with IL1R2 already being shown to be implicated in psoriasis and inflammatory bowel syndrome. The groups also found two 'desert DNA' regions on chromosomes two and 21, which are thought to regulate the genes responsible for causing AS.
'We have identified regions of our DNA that are strongly associated with susceptibility to ankylosing spondylitis,' says Professor Paul Wordsworth of Oxford University's Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences. 'This helps us better understand what is driving this disease and gives us direction for new treatments and diagnostic tests. There are many theories as to what triggers this condition but understanding which genes are involved is a major step forward which could lead both to new treatments but especially earlier diagnosis, which is badly needed in ankylosing spondylitis as some patients can wait up to a decade to be properly diagnosed' explained Dr John D Reveille, the study's principal investigator and professor and director of the Division of Rheumatology and Clinical Immunogenetics at The University of Texas Medical School at Houston, US.