RESUMO Atualmente não se sabe como os fatores genéticos podem influenciar o curso clínico da esclerose múltipla (EM). Objetivo: Examinamos o impacto dos polimorfismos CIITA −168A/G (rs3087456) e CIITA +1614G/C (rs4774) no risco de progressão da incapacidade, gravidade e resposta aos tratamentos imunomoduladores de primeira linha. Métodos: O DNA genômico foi extraído de amostras de sangue. Utilizamos o software ABI3730xl e GeneMapper v.4.0 (Applied Biosystems) para identificar variações genotípicas. Todos os pacientes foram acompanhados e reavaliados clinicamente em intervalos de três meses. A progressão da incapacidade foi medida pela EDSS e a gravidade da doença pelo MSSS. Resultados: Incluímos 37 homens e 80 mulheres. Não encontramos evidências sobre a influência dos SNPs estudados no EDSS e na resposta terapêutica aos fármacos avaliados. Realizamos uma análise de regressão logística com o MSSS e observamos uma evolução menos grave da EM associada aos tipos selvagens CIITA −168AA e CIITA +1614GG, pois a chance do paciente atingir MSSS2 e MSSS3 diminuiu em 61%/75%, e 66/75% respectivamente (p < 0,0001). Embora menos significativo, o CIITA +1614GC também foi relacionado com evolução menos grave da EM e a chance do paciente atingir o MSSS3 diminuiu 79% (p = 0,015). Nós também observamos que o genótipo CIITA −168GG foi mais frequente no MSSS2 e MSSS3 e teve uma razão de chance 40% menor para atingir forma mais grave da EM. Conclusão: Estes dados sugerem que os polimorfismos CIITA −168AA, CIITA +1614GG e CIITA +1614GC podem estar associados a um melhor curso clínico da EM. Este conhecimento pode ser útil para uma melhor compreensão da EM e o seu manejo terapêutico.

ABSTRACT It is currently unknown how genetic factors may influence the clinical course of multiple sclerosis (MS). Objective: We examined the impact of CIITA polymorphisms −168A/G (rs3087456) and +1614G/C (rs4774) on the risk of disability progression, severity and on responses to first-line immunomodulator treatments. Methods: Genomic DNA was extracted from blood samples. We used ABI3730xl and GeneMapper v.4.0 software to identify genotype variations. All patients were followed up and clinically reassessed at three-month intervals. Disability progression was measured by the Expanded Disability Status Scale and disease severity by the Multiple Sclerosis Spasticity Scale (MSSS). Results: We included 37 men and 80 women. We found no evidence regarding the influence of the single nucleotide polymorphisms studied in the Expanded Disability Status Scale or therapeutic response of the evaluated drugs. We performed a logistic regression analysis with the MSSS and found that a less severe MS course was associated with wild type CIITA −168AA and CIITA +1614GG, as the chance of the patient progressing to MSSS2 and MSSS3 decreased in 61% and 75% with CIITA −168AA and 66% and 75% with CIITA +1614GG, respectively (p < 0.0001). Although less significant, the CIITA +1614 GC also pointed to a less severe MS course and the chance of the patient progressing to MSSS3 decreased 79% (p = 0.015). We also observed that the CIITA −168GG genotype was more frequent in MSSS2 and MSSS3 and had 40% lower odds ratio to becoming more severe MS. Conclusion: These data suggest that CIITA −168AA, CIITA +1614GG and CIITA +1614 GC polymorphisms may be associated with a better MS clinical course. This knowledge may be useful for a better understanding of MS and its therapeutic management.

Introduction: The multiple sclerosis (MS) is a chronic disease of the central nervous system that affects mainly young adults. This disease is characterized by the spread of demyelinating lesions in time and space. This condition may be influenced by genetic factors as heterogeneity, incomplete penetrance, polygenic inheritance and epigenetic factors, which makes this complex disease a challenge for geneticists. Objectives: The aim of this study was to investigate the association between HLA alleles from DQA1, DQB1 and DRB1 loci (6p21.3), genetic polymorphisms -168A/G (rs3087456) and +1614 G/C (rs4774) in the CIITA gene (16p13) and susceptibility to MS in a miscegenated sample from Rio de Janeiro state, RJ, Brazil. Method: DNA samples from 52 patients with relapsing remitting multiple sclerosis (MSRR) [21 males (40.38%) and 31 females (59.62%)] and 116 healthy controls [46 males (39.65%) and 70 females (60.35%)] matched by race, sex and age were analyzed by techniques of PCR, SSP-PCR, electrophoresis and DNA sequencing. Results: A significant association between MS and HLA-DRB1*15:01 allele was observed [p value=.002; Odds Ratio (OR)=3.2], especially in women (p=.001; OR=4.9), which remained statistically significant after Bonferroni correction. Furthermore, it was observed that the polymorphism +1614 G/C, “C/C” profile, in association with the allele DRB1*15:01 influences the increased susceptibility to MS in women (p=.029; OR=5.6). In addition, it was observed that the "G/G" profile in CIITA polymorphism +1614G/C may be associated with the resistance to MS (p=.02; OR=0.23), as well as HLA-DRB1*11:02 (p=.02, OR=0.5). The HLA-DQB1*06:02 allele also has been implicated as a possible susceptibility factor for MS (p=.02; OR=1.8, data not confirmed after Bonferronís correction). Conclusion: Together, these results reinforce the polygenic nature of MS, and proposed that the CIITA gene, which is the regulator of the expression of HLA-D, is an additive factor to DRB1*15:01 allele, previously described as a genetic susceptibility factor to MS in Brazilians.