Investigators analyzed the various levels of genetic factors, including: 1.To analysis the key gene variants which associated with ADME affect the efficacy of Acitretin Capsules; 2.Direct full genetic sequencing of MHC genes, to explore the genetic variations of efficacy and side effects; 3. Direct sequencing of all exons in the gene in the patients of the response of serious and effectively, to explores the rare genetic variation may cause deterioration of treatment by Acitretin Capsules.