Manchester University. UK: Researchers led by the Arthritis Research UK Centre for Genetics and Genomics at The University of Manchester have identified genetic variants that are associated with psoriatic arthritis (PsA) but not with psoriasis, in the largest study of PsA ever published.
PsA is a common form of inflammatory form of arthritis causing pain
and stiffness in joints and tendons that can lead to joint damage.
Nearly all patients with PsA also have skin psoriasis and, in many
cases, the skin disease is present before the arthritis develops.
However, only one third of patients with psoriasis will go on to develop
PsA.
The researchers, who are part of a European consortium, say
that their work, which took three years to complete and is published in
Nature Communications, is a breakthrough because genetic changes have
been identified that increase the risk of PsA but not psoriasis.
Until
recently opinion was divided as to whether psoriatic arthritis was a
disease in its own right, or psoriasis combined with rheumatoid
arthritis.
The findings could, in future, lead to the
identification of people with psoriasis who are at risk of developing
psoriatic arthritis.
Dr John Bowes,
who led the analysis of the work, said: “Our study is beginning to
reveal key insights into the genetics of PsA that explain fundamental
differences between psoriasis and PsA. Our findings also highlight that
CD8+ cells are likely to be the key drivers of inflammation in PsA. This
will help us to focus on how the genetic changes act in those immune
cells to cause disease.”
The gene identified by the research team
lies on chromosome 5 and is not the first PsA-specific gene to be
identified. Patients who carry the HLA-B27 gene are also more likely to
develop PsA.
Professor Anne Barton,
a rheumatologist and senior author on the study explained: “By
identifying genes that predispose people to PsA but not psoriasis, we
hope in the future to be able to test patients with psoriasis to find
those at high risk of developing PsA. Excitingly, it raises the
possibility of introducing treatments to prevent the development of PsA
in those individuals in the future.”
Dr Stephen Simpson, director of research at Arthritis Research UK
added:” This is a significant finding. Not only does it help establish
PsA as a condition in its own right, but it could have major
implications in the way that patients with this condition are treated
and lead to the development of drugs specifically developed for PsA,
which are greatly needed.”
The research was funded by the National Institute for Health Research Manchester Musculoskeletal Biomedical Research Unit.