Prevalence of CCR5-Δ32 and CCR2-V64I polymorphisms in a mixed population from northeastern Brazil.

Chemokines are low-molecular weight proteins that play a key role in inflammatory processes. Genomic variations in chemokine receptors are associated with the susceptibility to various diseases. Polymorphisms in chemokine receptor type 5 (CCR5)-Δ32 and CCR2-V64I are related to human immunodeficiency virus infection resistance, which has led to genetic association studies for several other diseases. Given the heterogeneous distribution of these polymorphisms in different global populations and within Brazilian populations, we analyzed the prevalence of CCR5-Δ32 and CCR2-V64I polymorphisms in a mixed population from northeastern Brazil. The study included 223 individuals from the general population of the city of Parnaíba, Piauí, who had a mean age of 73 years. Of these individuals, 37.2% were men and 62.8% were women. Polymorphisms were analyzed using DNA extracted from peripheral blood leukocytes by using polymerase chain reaction alone (CCR5-Δ32) or accompanied by restriction endonuclease digestion (CCR2-V64I). In both cases, the genotypes were determined using 8% polyacrylamide gel electrophoresis and silver nitrate staining. The population conformed to Hardy-Weinberg equilibrium for both the loci studied. No individuals were homozygous for allele-Δ32, which was present in 1.8% of the population, whereas allele-64I was present in 13.9% of the participants studied; 74.9% were homozygous for the wild-type allele, while 22.4 and 2.7% were heterozygous and homozygous for the mutant allele, respectively. Additional studies are needed to investigate the relationship between these polymorphisms and disease etiopathogenesis in reference populations.

Study of polymorphic variants of the serotonin 2A receptor gene (5-HT2A) and its possible effects on smoking habits of a population from northeastern Brazil.

Previous studies have revealed a genetic component, including genetic polymorphisms in the serotonergic pathway, particularly in the serotonin receptor gene (5-HT2A). The aim of this study was to investigate associations of the T102C (rs6313) and A-1438G (rs6311) polymorphisms with tobacco use in a population from northeastern Brazil. We evaluated these polymorphisms in 135 nonsmokers and 135 smokers using polymerase chain reaction-restricted fragment length polymorphism. The distribution of allele and genotype frequencies and associations of polymorphisms with smoking were assessed with the chi-squared (χ(2)) test, the Fisher exact test, and odds ratio (OR) with a 95% confidence interval (CI). There were no differences in the distribution of genotype and allele frequencies between nonsmokers and smokers for A-1438G (P = 0.80) and T102C (P = 0.35). However, these polymorphisms were significantly associated with habit frequency (A/G: P = 0.02, OR = 6.87, 95%CI = 1.23-38.31, P = 0.04; A/G+G/G: P = 0.04, OR = 3.67, 95%CI = 1.06-12.75, P = 0.07), age of onset (C/C: P = 0.02, OR = 3.26, 95%CI = 1.17-9.07, P = 0.03, and nicotine dependence level (A/G: P = 0.02, OR = 3.28, 95%CI = 1.17-9.18, P = 0.04; A/G+G/G: P = 0.04, OR = 2.81, 95%CI = 1.13-6.99, P = 0.04; T/C: P = 0.03, OR = 3.12, 95%CI = 1.13-8.57, P = 0.04; T/C+C/C: P = 0.02, OR = 3.06, 95%CI = 1.22-7.70, P = 0.02). Therefore, these polymorphisms may not contribute significantly to smoking initiation, they do appear to be associated with habit maintenance.

Association of the rs7903146 and rs12255372 polymorphisms in the TCF7L2 gene with type 2 diabetes in a population from northeastern Brazil.

Approximately 200 million people suffer from type 2 diabetes (T2D) worldwide, and the rapid increase in the prevalence of this disease is likely a result of multiple environmental factors, such as increased food intake and decreased physical activity in genetically predisposed individuals. Different population studies have demonstrated a strong association of two polymorphic variations in the TCF7L2 gene, the noncoding single nucleotide polymorphisms (SNPs) rs7903146 (C/T) and rs12255372 (G/T), with T2D. Herein, we analyzed the association of these SNPs with T2D in a population from northeastern Brazil. Our results showed that the genotype and allele frequencies in TCF7L2 rs7903146 and rs12255372 were similar in the patient and control groups (P > 0.05). In addition, the allele frequencies were not significantly associated with T2D risk [rs7903146: odds ratio (OR) = 0.95, 95% confidence interval (CI) = 0.52-1.76, P = 1.00, and rs12255372: OR = 1.38, 95%CI = 0.72-2.62, P = 0.41]. These data suggest that the TCF7L2 SNPs rs7903146 and rs12255372 may not significantly contribute to T2D susceptibility in this population. However, our results may reflect the small number of subjects. Alternatively, these results may be attributable to specific ethnic effects, as most of the previously reported associations were demonstrated with predominantly European populations. To reach a definitive conclusion on the role of such gene variants for T2D in mixed populations, additional efforts are necessary to replicate this study with larger populations from areas with more ethnic heterogeneity.

Differential expression of E-cadherin gene in human neuroepithelial tumors.

Cadherins are cell-to-cell adhesion molecules that play an important role in the establishment of adherent-type junctions by mediating calcium-dependent cellular interactions. The CDH1 gene encodes the transmembrane glycoprotein E-cadherin which is important in maintaining homophilic cell-cell adhesion in epithelial tissues. E-cadherin interacts with catenin proteins to maintain tissue architecture. Structural defects or loss of expression of E-cadherin have been reported as a common feature in several human cancer types. This study aimed to evaluate the expression of E-cadherin and their correlation with clinical features in microdissected brain tumor samples from 81 patients, divided into 62 astrocytic tumors grades I to IV and 19 medulloblastomas, and from 5 white matter non-neoplasic brain tissue samples. E-cadherin (CDH1) gene expression was analyzed by quantitative real-time polymerase chain reaction. Mann-Whitney, Kruskal-Wallis, Kaplan-Meir, and log-rank tests were performed for statistical analyses. We observed a decrease in expression among pathological grades of neuroepithelial tumors. Non-neoplasic brain tissue showed a higher expression level of CDH1 gene than did neuroepithelial tumors. Expression of E-cadherin gene was higher in astrocytic than embryonal tumors (P = 0.0168). Low-grade malignancy astrocytomas (grades I-II) showed higher CDH1 expression than did high-grade malignancy astrocytomas (grades III-IV) and medulloblastomas (P < 0.0001). Non-neoplasic brain tissue showed a higher expression level of CDH1 gene than grade I malignancy astrocytomas, considered as benign tumors (P = 0.0473). These results suggest that a decrease in E-cadherin gene expression level in high-grade neuroepithelial tumors may be a hallmark of malignancy in dedifferentiated tumors and that it may be possibly correlated with their progression and dissemination.

Differential expression of E-cadherin gene in human neuroepithelial tumors

Cadherins are cell-to-cell adhesion molecules that play an important role in the establishment of adherent-type junctions by mediating calcium-dependent cellular interactions. The CDH1 gene encodes the transmembrane glycoprotein E-cadherin which is important in maintaining homophilic cell-cell adhesion in epithelial tissues. E-cadherin interacts with catenin proteins to maintain tissue architecture. Structural defects or loss of expression of E-cadherin have been reported as a common feature in several human cancer types. This study aimed to evaluate the expression of E-cadherin and their correlation with clinical features in microdissected brain tumor samples from 81 patients, divided into 62 astrocytic tumors grades I to IV and 19 medulloblastomas, and from 5 white matter non-neoplasic brain tissue samples. E-cadherin (CDH1) gene expression was analyzed by quantitative real-time polymerase chain reaction. Mann-Whitney, Kruskal-Wallis, Kaplan-Meir, and log-rank tests were performed for statistical analyses. We observed a decrease in expression among pathological grades of neuroepithelial tumors. Non-neoplasic brain tissue showed a higher expression level of CDH1 gene than did neuroepithelial tumors. Expression of E-cadherin gene was higher in astrocytic than embryonal tumors (P = 0.0168). Low-grade malignancy astrocytomas (grades I-II) showed higher CDH1 expression than did high-grade malignancy astrocytomas (grades III-IV) and medulloblastomas (P < 0.0001). Non-neoplasic brain tissue showed a higher expression level of CDH1 gene than grade I malignancy astrocytomas, considered as benign tumors (P = 0.0473). These results suggest that a decrease in E-cadherin gene expression level in high-grade neuroepithelial tumors may be a hallmark of malignancy in dedifferentiated tumors and that it may be possibly correlated with their progression and dissemination.