There is a large amount of evidence suggesting that there is a genetic predisposition to psoriasis (2). However, there is no one specific psoriasis gene, but instead, there are a number of genetic characteristics which make a patient more likely to develop the condition (1).
Several studies have shown that there is a family history of psoriasis in 30% to 50% of psoriasis cases.
Research on monozygotic twins (identical twins) has however shown that in 70% of cases, both twins were subject to psoriasis (1). If heredity was the sole cause, there would be a 100% match. These findings therefore show that psoriasis depends on other factors.
Our knowledge of the genes associated with psoriasis is currently incomplete. However, studies of families of people with psoriasis have demonstrated that there are chromosome regions associated with the condition (1). These clusters of genes leading to skin inflammation vary from one family to another and from one patient to another.
Researchers think that in a few years they will be able to identify different treatments appropriate to the genetic characteristics of psoriasis patients (1).
Some groups, such as native Americans from the Andes and Eskimos, do not get psoriasis. This could possibly be explained by genetic differences coupled with environmental factors.
Read more about genetic factors.