1. Department of Pediatrics, University of Texas Southwestern Medical Center,Dallas, TX 75235-8591, USA.
2. Psoriasis Center, Baylor University Medical Center, Dallas, TX 75246, USA.
3. Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
4. Department of Dermatology, Oregon Health Sciences University, Portland, OR 97201, USA.