More than a million people in the UK are affected by psoriasis - an auto-immune disease that causes sore, itchy patches of red, scaly skin. Between 10% and 30% of patients also develop a painful form of arthritis.
Researchers in the US scanned millions of DNA variations to find those that occur more frequently in people with the condition. This allowed them to home in on 18 "hotspots", or "loci", in the genetic code - seven of which showed consistently strong associations with the condition.
The genes responsible for psoriasis have until now proved elusive, even though the condition has a strong genetic component. A child with two affected parents has a 50% chance of developing psoriasis, while siblings have a three to six-fold increased risk.
Dr Goncalo Abecasis, from the University of Michigan School of Public Health in Ann Arbor, who led the research, said: "This discovery highlights the role of several genes in mediating the immune responses that result in psoriasis."
He said that future drugs which target genes at the sites, or their proteins, may provide promising new therapies.