Investigação do polimorfismo do gene do receptor da vitamina D em pacientes com psoríase

Abstract

Psoriais is a chronicle inflammatory skin disease characterized by appearance of erytematous, pruriginous scaling plaques strongly demarcated specially in knees, elbows, scalp and intergluteus groove, light spear body regions. The name comes from “Psora” a Greek word that means to itch. It’s presente in 2% of population and hasn’t a correlation with higher mortality or morbidity. In it’s pathogenesis immunological, genetics and cell-to-cell interactions play some role. It seams to have a disfunction in T CD4 cells, that after contact with antigen presenting cell from epidermis, became activated and become to present surface receptors and to accumulate in epidermis. Since the first studies, genetic behavior became clear. Nevertheless a specifc gene wasn’t blamed yet. Many genes related to higher risk of present Psoriasis has been reported, among them we drive attention to the ones called PSOR 1 to PSOR7 in whích some genetic loci as HLA-CwO6 and DR7 had been blamed. Vitamin D has it’s own role in some metabolic ways, acting either by non-nuclear ways generating second messengers or nuclear ways, by heterodimerization with Vitamin D receptor (VDR) in the gene expression, activating or deactivating responsible regions of genes (VDRE). Vitamin D receptor gene polymorphism had been studied in some populations with conflicting results. We investigated the Taq I, Fok I and Bsm I polymorphism using RFLP assays with restriction enzymes. Skin biopsies from psoriasis patients were compared with blood samples from non-psoriasis persons using an index of severity. Logistic regression did not reveal significant differences between group genotypes. Nor did Fisher’s test disclose significant association between genotypes and the severity index. These findíngs were in agreement with the ínternational literature. Our conclusion was that vdr polymorphism is not associated with the genesis of psoriasis and differences between some population groups may be due to the “founding effect”.