1. Department of General Practice, Erasmus MC—University Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
2. General Practice, Dorpsstraat 61, 3927 BB Renswoude, The Netherlands
3. Department of Dermatology and Venereology (Pediatric Dermatology), Erasmus MC—University Medical Center Rotterdam/Sophia Children's Hospital, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands