961 resultados para GENE POLYMORPHISMS


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Molecular biology techniques are of help in genetic improvement since they permit the identification, mapping and analysis of polymorphisms of genes encoding proteins that act on metabolic pathways involved in economically interesting traits. The somatotrophic axis, which essentially consists of growth hormone releasing hormone (GHRH), growth hormone (GH), insulin-like growth factors I and II (IGF-I and IGF-II), and their associated binding proteins and receptors (GHRHR, GHR, IGF-IR and IGF-IIR), plays a key role in the metabolism and physiology of mammalian growth. The objectives of the present study were to estimate the allele and genotype frequencies of the IGF-I/SnaBI, IGF-IR/TaqI and GHRH/HaeIII gene polymorphisms in different genetic groups of beef cattle and to determine associations between these polymorphisms and growth and carcass traits. For this purpose, genotyping was performed on 79 Nellore animals, 30 Canchim (5/8 Charolais+3/8 Zebu) animals and 275 crossbred cattle originating from the crosses of Simmental (n=30) and Angus (n=245) sires with Nellore females. In the association studies, traits of interest were analyzed using the GLM procedure of SAS and least square means of the genotypes were compared by the Tukey test. Associations of IGF-I/SnaBI genotypes with body weight and subcutaneous backfat were significant (p < 0.05), and nearly significant for longissimus dorsi area (p=0.06), with the 1313 genotype being favorable compared to the AB genotype. No significant associations were observed between this polymorphism and weight gain or carcass yield (P > 0.05). The IGF-IR/TaqI and GHRH/HaeIII polymorphisms showed no association with production traits. (c) 2004 Elsevier B.V All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Background: Duffy blood group polymorphisms are important in areas where Plasmodium vivax predominates, because this molecule acts as a receptor for this protozoan. In the present study, Duffy blood group genotyping in P. vivax malaria patients from four different Brazilian endemic areas is reported, exploring significant associations between blood group variants and susceptibility or resistance to malaria.Methods: the P. vivax identification was determined by non-genotypic and genotypic screening tests. The Duffy blood group was genotyped by PCR/RFLP in 330 blood donors and 312 malaria patients from four Brazilian Amazon areas. In order to assess the variables significance and to obtain independence among the proportions, the Fisher's exact test was used.Results: the data show a high frequency of the FYA/FYB genotype, followed by FYB/FYB, FYA/FYA, FYA/FYB-33 and FYB/FYB-33. Low frequencies were detected for the FYA/FY(X), FYB/FY(X), FYX/FY(X) and FYB-33/FYB-33 genotypes. Negative Duffy genotype (FYB-33/FYB-33) was found in both groups: individuals infected and non-infected (blood donors). No individual carried the FY(X)/FYB-33 genotype. Some of the Duffy genotypes frequencies showed significant differences between donors and malaria patients.Conclusion: the obtained data suggest that individuals with the FYA/FYB genotype have higher susceptibility to malaria. The presence of the FYB-33 allele may be a selective advantage in the population, reducing the rate of infection by P. vivax in this region. Additional efforts may contribute to better elucidate the physiopathologic differences in this parasite/host relationship in regions endemic for P. vivax malaria, in particular the Brazilian Amazon region.

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Our objective was to determine how the distribution of red blood cell diseases is related to malaria occurrence in north Brazil, a region endemic for malaria. We evaluated the incidence of two mutations in the HFE gene, H63D and C282Y, in two study groups: a control blood donor group, with no indication of malaria infection, and a group constituted of malaria patients of four states of the Amazonian region. The hemoglobin polymorphisms were obtained by HPLC and classical laboratory methodologies, and the two mutations in the HFE gene were assayed by PCR-RFLP. We found a high frequency of alpha thalassemia, but there were no significant differences between blood donors and malaria patients. There were also no significant differences in the frequencies of HbA(2); however, the frequency of HbF was significantly different in individuals with malaria from Para and Rondonia. The mean number of reticulocytes was significantly reduced in the blood donors from the northern region, suggesting an adaptive strategy of these populations to parasitic attack by Plasmodium. Most individuals were heterozygous for the H63D allele of the HFE gene in both study groups. In the blood donors group, the greatest frequency of the H63D allele was found in Caucasians of all the states. In the malaria patients group in Rondonia, there was a high frequency of the H63D allele among the non-Caucasians. In the other states, and in the malaria patients group, the H63D allele was the most frequent among the Caucasians. Based on our results, we suggest that the maintenance of polymorphism of the mutations in the gene HFE can be explained by selective factors other than malaria, or it is due to simple allelic oscillation and by the constant gene flow among the populations in Brazil.

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The objective of the present study was to estimate the allele and genotype frequencies of the CSN3/Hinfl and LGB/HaeIII gene polymorphisms in beef cattle belonging to different genetic groups, and to determine the effects of these polymorphisms on growth and carcass traits in these animals, which are submitted to an intensive production model. Genotyping was performed on 79 Nelore, 30 Canchim (5/8 Charolais + 3/8 Zebu) and 275 crossbred cattle originating from the crosses of Simmental (n = 30) and Angus (n = 245) sires with Nelore females. Body weight, weight gain, dressing percentage, longissimus dorsi area and backfat thickness were fitted using the GLM procedure, and least square means of the genotypes were compared by the F test. The results showed that the CSN3/Hinfl and LGB/HaeIII polymorphisms did not have any effect on growth or carcass traits (p > 0.05). Copyright by the Brazilian Society of genetics.

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Background: Chronic inflammation and gastric carcinogenesis show a close association, so gene polymorphisms that modify the intensity of the inflammatory response may contribute to variations in gastric cancer risk. Aims: The purpose of this study was to investigate the combined effect of the pro- and anti-inflammatory cytokines and toll-like receptors polymorphisms on the chronic gastritis and gastric cancer risk in a Brazilian population sample. Methods: We evaluated 669 DNA samples (200 of gastric cancer [GC], 229 of chronic gastritis [CG], and 240 of healthy individuals [C]). Ten polymorphisms were genotyped: IL-1RN and TLR2 -196 to -174 del using the allele-specific PCR method and TNF-A (rs1800629; rs1799724), TNF-B (rs909253), IL-8 (rs4073; rs2227532), IL-10 (rs1800872) and TLR4 (rs4986790; rs4986791) using PCR-RFLP. Results: Polymorphisms TNF-A-308G/A, IL-8-251A/T, TNF-B + 252A/G and TLR4 + 1196C/T were not associated with risk of any gastric lesion. However, an association with increased risk for GC was observed for polymorphisms IL-1RNL/2 (p < 0.001), TNF-A-857C/T (p = 0.022), IL-8-845T/C (p < 0.001), IL-10-592C/A (p < 0.001), TLR2ins/del (p < 0.001), and TLR4 + 896A/G (p = 0.033). In CG, an association was observed only with polymorphisms IL-1RNL/2 and IL-10-592A/C (p < 0.001 for both). A combined analysis of these six polymorphisms associated with GC revealed a profile with two to four combined genotypes which confer a higher risk of gastric carcinogenesis, with an OR increased 2.95-fold to 50.4-fold, highlighting the combinations IL-1RN2/TNF-A-857T/IL-8-845C, IL-1RN2/IL-8-845C/TLR2del, IL-1RN2/IL-10-592A/TLR4 + 896G, IL-10-592A/TLR2del/ TLR4 + 896G, and IL-1RN2/TNFA-857T/IL8-845C/TLR2del. Conclusions: Our findings evidenced that the combined effect of polymorphisms in genes involved in the inflammatory process may potentiate the risk of gastric cancer, thus emphasizing the importance of evaluating multiple polymorphisms together. © 2012 Springer Science+Business Media New York.

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