P29 Frequency of HLA-C*06:02 in a multiracial population in Brazil: a comparison between psoriasis patients and healthy controls

Abstract Psoriasis is a chronic, inflammatory, systemic and genetic-based disease with prevalences varying from 0.09 and 11.43% around the world. In Brazil, the overall prevalence is 1.31%, although there are significant differences among regions. The genetic background is still a matter of study, and many genes and loci of susceptibility have been identified. PSORS1 is the most important locus related to the risk of the disease, and inside it, HLA-C*06:02 is the main gene related to psoriasis. When two copies of this gene are carried by an individual, it increases 50-fold odds of developing the disease. It also participates in the clinical presentation, because the presence of HLA-C*06:02 is related to the early development of symptoms (Type 1 psoriasis), higher incidence of the Koebner phenomenon, and higher response to streptococcal throat infection as a trigger to the disease. Moreover, it is related to the response to treatment. The population in Brazil differs from the rest of Latin America, because colonization involved Portuguese, native Brazilians and African population. On the other hand, in the rest of Latin America miscegenation occurred between Spanish, native people from America (distinct from the ones in Brazil) and different degrees of participation of African population. Inside Brazil, which is a continental country, there are also significant differences between populations of distinct regions and, therefore, possibly diverse genetics. In Brazil, the last studies were performed before the last update in nomenclature, and none of them showed results regarding HLA-C*06:02. Our research has typified 40 patients with psoriasis and 104 healthy patients for HLA*C06:02 from the Southeast region of Brazil. The frequency of HLA-C*06:02 (allele G) in the group of patients was 27.78% and in controls was 14.44% (odds ratio 2.28; confidence interval 1.5–3.47), P = 0.00011. The Bonferroni correction was applied, and P-value was adjusted (P = 0.004). Also, when the patients were divided between mild and moderate to severe disease, there was no difference in frequency of this allele between the two groups (P = 0.48377). This study was funded by FAPERJ, www.faperj.br.