Frequency of the CCRdelta32 allele in Brazilians: a study in colorectal cancer and in HTLV-I infection

Abstract

The identification of a 32-bp deletion in the cc-chemokine receptor-5 gene (CCR5delta32 allele) that renders homozygous individuals highly resistant to HIV infection has prompted worldwide investigations of the frequency of the CCR5delta32 allele in regional populations. It is important to ascertain if CCR5delta32 is a factor to be considered in the overall epidemiology of HIV in individual populations. With this in mind we determined the CCR5delta32 allele frequency in a large sample (907 individuals) of the southeastern Brazilian urban population, stratified as follows: 322 healthy unrelated individuals, 354 unselected colorectal cancer patients, and 229 blood donors. The three groups displayed essentially identical allelic frequencies of CCR5delta32 and pairwise comparisons did not show significant differences. Thus, our results can be pooled to provide a reliable estimate of the CCR5delta32 allele frequency in the southeastern Brazil of 0.053 ± 0.005. The blood donors comprised 50 HTLV-I serologically negative individuals, 115 non-symptomatic individuals HTLV-I positive by ELISA but with indeterminate Western blot results, 49 healthy blood donors HTLV-I positive both at ELISA and Western blot and 15 patients with clinical spinal cord disease (HAM). A suggestive trend was observed, with the CCR5delta32 frequencies decreasing progressively in these four categories. However, when we applied Fischer's exact test no significant differences emerged. We believe that further studies in larger cohorts should be performed to ascertain whether the CCR5delta32 allele influences the chance of becoming infected or developing clinical symptoms of HTLV-I infection.<br>A observação de que indivíduos homozigotos para uma deleção de 32 pares de base no gene que codifica para o receptor 5 de cc-quimiocinas apresentam um menor risco de contrair a infecção por HIV-1 levou à investigação da freqüência deste polimorfismo em várias populações mundiais. É importante investigar se o CCR5delta32 é um fator a ser considerado na epidemiologia do HIV em populações individuais. Com estes pressupostos em mente nós estabelecemos a freqüência do CCR5delta32 em uma grande amostra (907 indivíduos não-relacionados) da população urbana do sudeste brasileiro, estratificada da seguinte maneira: 322 indivíduos sadios, 354 pacientes com câncer colorretal e 229 doadores de sangue. Os três grupos apresentaram essencialmente a mesma freqüência alélica de CCR5delta32 e a comparação par-a-par não revelou diferenças significativas. Assim, os nossos resultados podem ser agrupados para fornecer uma estimativa confiável de 0,053 ± 0,005 da freqüência alélica de CCR5delta32. Os doadores de sangue compreendiam 50 indivíduos soronegativos para HTLV-I, 115 indivíduos assintomáticos por ELISA mas com resultados indeterminados em Western blot, 49 indivíduos soropositivos para HTLV-I mas assintomáticos e 15 indivíduos soropositivos para HTLV-I sintomáticos com mielopatia. Foi observado um sugestivo gradiente decrescente da freqüência alélica de CCR5delta32 nestas cat...

CCR5 status and metastatic progression in colorectal cancer

“…The mechanisms behind this phenomenon are unknown so far. The functionally inactive homozygous version of Δ32-CCR5 is present in a low number of patients (frequencies of homozygous individuals range between 1,1% 49 and 3% in the general Caucasian population 50,51 ) but the heterozygous situation is more likely (ranging from 10% to 20% according to studies). 49,52 Interestingly, heterozygous individuals only express 20-30% of the wild-type protein on their cell surface.…”

High frequency of the CCR5delta32 variant among individuals from an admixed Brazilian population with sickle cell anemia

“…The prevalence of the CCR5D32 allele in the southern European-derived Brazilian population investigated was 4.4%. The prevalence of the CCR5D32 allele was described as 3.5% in an urban Brazilian southeast population (10) and, more recently, also in southeast Brazilian Caucasoids, as 5.3% (11). In the populations from the Mediterranean area with whom European-derived Brazilians share common ancestors, this frequency ranged from 4 to 9% (8).…”

Frequency of the CCR5‐Δ32 polymorphism in the Maltese population at birth

“…, 2005). This polymorphism was also found in other populations of European descent (Brazilian) (Pereira et al. , 2000), but was absent in African and most Asian populations (Yudin et al.…”