Risk Factors

Between 5.8 and 7.5 million Americans have psoriasis. Risk factors for psoriasis include:

Age under 20. About 40% develop the condition before age 20. Psoriasis (most often plaque psoriasis) can even occur in infants.
Climate. Some studies have found that the disorder develops earlier and more frequently in colder climates. For example, psoriasis occurs more frequently in African-Americans and in Caucasians who live in colder climates than in people of any ethnicity who live in Africa.
Ethnicity. Psoriasis is uncommon in Native Americans of either North or South American descent.
Family history of the disease. About 35% of those with psoriasis have one or more family members with the disorder.
Male gender. Some studies have indicated that more men than women have psoriasis.

Review Date: 12/21/2006
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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