AAD: Psoriasis Age of Onset Similar in Twins
Maternal history of the disease boosts risk more than paternal history
TUESDAY, Aug. 1 (HealthDay News) -- A study of twin pairs sheds new light on the genetic influences of psoriasis, with researchers finding that the age of onset is similar in twin-pairs where both develop the disease. They also found maternal history of the disease boosts risk more than paternal history, according to the results presented at Academy '06, the American Academy of Dermatology's summer meeting in San Diego.
Theodore Alkousakis, M.D., of Iowa City, Iowa, and colleagues evaluated 156 twins from the California Twin Program Database as well as responses from unaffected twins. Seventy-two percent were from dizygotic twin-pairs and the remainder were from monozygotic twin-pairs. Concordance was defined as the presence of psoriasis in both twins of a pair, with no regard to their status as fraternal or identical twins.
Fourteen of 144 monozygotic twins (32 percent) had a twin who also developed psoriasis, while 19 of 105 (18 percent) of fraternal twins had an affected twin. The mean age of affected twins was 52, and for unaffected twins 53 years, and the sample was about equally divided between men and women. Offspring of women with psoriasis were more likely to develop the skin condition, with 21 percent of offspring of mothers with psoriasis having psoriasis, but just 3 percent of offspring of psoriatic males. Women tended to get the disease earlier than men did.
"The present study demonstrated gender, zygosity, and concordance-specific characteristics, disease associations, and demogeographic information which may contribute to the understanding of the genetic and environmental factors associated with psoriasis," the authors conclude.