Genetic Analysis of Psoriasis and Psoriatic Arthritis

This study will examine the genetic basis of psoriasis and psoriatic arthritis. It is known that genes play an important role in determining who gets psoriasis or psoriatic arthritis. This study will look for specific gene variants (alleles) that run in families with these conditions, or are found more often in people with these conditions than in those without them.

Participants for this study were identified through the dermatology services of the University of Michigan Medical Center, the Ann Arbor Veterans Affairs Medical Center, the University of Kiel, and Henry Ford Hospital. Additional families were provided by the National Psoriasis Foundation Tissue Bank. They include people with psoriasis or psoriatic arthritis, or both, in addition to some family members of patients. Only families in which the age of the patient at disease onset was below 40 years are included. Patients were included if they had lesions covering more than 1 percent of their total body surface area or if at least two skin, scalp, nail, or joint lesions were diagnosed as psoriasis. Healthy volunteers are also enrolled as control subjects.

Participants undergo the following procedures, as follows:

Patients with psoriasis and people without psoriasis who have multiple family members with the disease

* Skin evaluation * Photographs of lesions for documentation

Patients with psoriatic arthritis and people without psoriatic arthritis who have multiple family members with the disease

* Joint evaluation and possibly ultrasound * Joint X-rays or review of existing X-rays

Patients with psoriasis only, with psoriatic arthritis, and healthy volunteers

* Blood draw of 30 milliliters. Some of the blood collected will be used to test for rheumatoid factor and C-reactive protein in patients with psoriatic arthritis. * Periodic questionnaires to update health status information