Psoriasis is a relatively common chronic and recurrent skin condition that results in a build-up of dead cells in patches on the skin surface, giving the affected areas of the skin a red, thickened appearance. There are several types and symptoms range from mild to severe. The cause of psoriasis is not known, although it is known that psoriasis has a large genetic component and the chance of close relatives of an affected person also developing psoriasis is greater than for people who have no family history.
A number of genes that cause a susceptibility to the development of psoriasis are located on different chromosomes. The pattern of inheritance is likely to be multifactorial in nature so that where there is a genetic susceptibility to psoriasis, an environmental trigger(s) such as bacterial infections or stress is also required for the condition to occur.