Psoriasis sufferers have been given new hope after several genetic variants linked to the disease were identified.
Researchers from the University of Michigan School of Public Health looked at millions of DNA variations to find those that occur more frequently in people with psoriasis.
The results showed there are 18 "hotspots" evident in the genetic code. Of these "loci", seven had consistently strong associations with the condition.
Researchers, writing in the journal Nature Genetics, said new therapies could be developed by targeting future drugs to genes at the sites, or their proteins.
Psoriasis is an auto-immune disease that causes sore, itchy patches of red, scaly skin. Between 10% and 30% of the one million people who suffer with it in the UK also develop a painful form of arthritis.
One area of DNA highlighted by the study contains changes to a gene called IL-23A, which may affect the immune response underlying psoriasis. Two other genes, TNFAIP3 and TNIP1 that are activated by a key inflammation signalling molecule also showed a strong association with the disease.
Lead researcher, Dr Goncalo Abecasis, said: "This discovery highlights the role of several genes in mediating the immune responses that result in psoriasis.
"Some of the highlighted genes, like those in the IL-23 pathway are already targeted by effective psoriasis therapies. Others, like TNFAIP3 and TNIP1, may become targets for the psoriasis treatments of the future."
"I am delighted to hear this latest news. My husband and daughter both suffer with psoriasis. Unfortunately, my husband also suffers with the associated condition psoriatic arthritis. I will be following this latest discovery with a huge personal interest." - Gill Belchamber, Wiltshire
"Very encouraging as I suffer with this and arthropathy." - Annette Murfin, Muswell Hill