The CCR5 chemokine receptor has been implicated in the pathogenesis of multiple sclerosis (MS). This research was carried out to investigate the association between the CCR5-Δ32 deletion in 124 patients with MS from Southern Brazil. Ninety-eight (79.0%) patients presented with relapsingremitting MS (RR-MS), 17 (13.7%) secondary progressive MS (SP-MS), 8 (6.5%) primary progressive MS (PP-MS) and one (0.8%) clinically isolated syndrome (CIS). The control group consisted of 127 healthy blood

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... from the same geographic region. The disease severity was assessed clinically using the Expanded Disability Status Scale (EDSS). Genomic DNA was extracted from peripheral blood cells and the genetic polymorphism was evaluated by polymerase chain reaction. Of the MS patients, 85 (68.5%) were females (p=0.0093). The CCR5-Δ32 frequency among the controls was 5.5%, and did not differ from that observed among the MS patients (4.8%) (p=0.7337). The mean (±SD) age at disease onset among the carriers and non-carriers of the CCR5-Δ32 allele was 31.7 (±11.1) and 36.6 (±12.0) years, respectively (p=0.1312). The duration (±SD) of the disease was 11.2 (±12.9) and 7.7 (± 5.6) years among the CCR5-Δ32 heterozygous, and CCR5 wild type, respectively (p=0.396). The mean (±SD) EDSS among the MS patients carriers and non-carriers of the CCR5-Δ32 allele was 2.4±1.2 and 2.67±2.2, respectively (p=0.9796). The MRI findings in MS patients with the CCR5-Δ32 genotype exhibited lower positive gadolinium enhancing-imaging (p=0.0013) and lower brain atrophy (p=0.1333) than MS patients with the CCR5 wild-type genotype. Despite that the differences were not significant, the results suggested that the disease onset and progression to disability may be prolonged in MS carriers of CCR5-Δ32, and CCR5-Δ32 could be considered a favorable prognostic biomarker of MS. Further studies comprising larger numbers of individuals carrying non-wild-type haplotypes are needed to determine CCR5-Δ32 involvement in the specific process of MS pathology and pathogenesis.