Dr Sarah Tansley

“DM is a very variable disease and this makes its effects very difficult to predict. The autoantibodies are detectable using a simple blood test and we hope that, as well as helping to diagnose JDM, they will also give doctors more accurate information about how a patient’s disease might progress."

Autoantibodies in JDM

Professor McHugh’s team at the University of Bath have been investigating the potential use of autoantibodies in juvenile dermatomyositis and have analysed blood samples from over 400 JDM patients. Autoantibodies can be found in many rheumatological diseases and some are unique to dermatomyositis. The group have done extensive research on autoantibodies in adult patients with myositis and have been responsible for discovering new autoantibodies in patients with both myositis and scleroderma. With current laboratory techniques an autoantibody can be identified in roughly 60% of all JDM samples tested. The team believes that all patients with JDM will have an autoantibody and that there are more autoantibodies still to be discovered.

Dr Sarah Tansley supported by grants from the BMA and the Bath Institute of Rheumatic Diseases has been investigating the clinical features of patients with JDM with different types of autoantibody. “We have been able to show that different autoantibodies are associated with different subgroups of disease. Patients with anti-NXP2 in their blood, for example, appear much more likely to develop calcinosis and patients with anti-MDA5 are less weak”.

“JDM is a very variable disease and this makes its effects very difficult to predict. The autoantibodies are detectable using a simple blood test and we hope that, as well as helping to diagnose JDM, they will also give doctors more accurate information about how a patient’s disease might progress. This will help them to look out for and treat any complications that occur at an early stage, and will also allow them to give more detailed information to patients and their families.”

“We have also been able to identify autoantibody subgroups that seem to respond less well to standard treatment and need stronger drugs. We believe that subdividing patients by autoantibody type is important in clinical trials of any new potential treatments for JDM. While work is currently at a very early stage it is possible that in the future different treatments will be recommended for different autoantibody subgroups.”

“We can identify the same autoantibodies in children with JDM as are found in adults but the frequencies are different: Autoantibodies that are common in adults are typically rare in children and vice versa. We don’t yet know what causes autoantibodies to develop or why people with myositis have different autoantibodies but we think it may relate to a person’s genetic make-up and possibly different disease triggers. Studying the differences between autoantibody groups and between adults and children might help us understand better why people develop myositis.”

The team are working with doctors to make autoantibody testing more widely available.