Researchers at Washington University School of Medicine in St Louis have found seven new sites of DNA variation that increases the risk of psoriasis.
Genetic research into the autoimmune disease discovered seven novel DNA variations linked to psoriasis including DNA variations on chromosome 4 which are strongly linked to psoriatic arthritis.
These variations have also been associated with type 1 diabetes, rheumatoid arthritis, Grave’s disease and celiac disease.
Lead researcher of the study Dr Anne Bowcock, professor of genetics at the School of Medicine, said: "Common diseases like psoriasis are incredibly complex at the genetic level.
"Our research shows that small but common DNA differences are important in the development of psoriasis. Although each variation makes only a small contribution to the disease, patients usually have a number of different genetic variations that increases their risk of psoriasis and psoriatic arthritis."
An estimated seven million Americans suffer from psoriasis, ten to 30 per cent of which go on to develop psoriatic arthritis.