Superoxide dismutase, catalase, glutathione peroxidase and gluthatione S-transferases M1 and T1 gene polymorphisms in three Brazilian population groups

Antioxidants such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX1) reduce the oxidation rates in the organism. Gluthatione S-transferases (GSTs) play a vital role in phase 2 of biotransformation of many substances. Variation in the expression of these enzymes suggests individual differences for the degree of antioxidant protection and geographical differences in the distribution of these variants. We described the distribution frequency of CAT (21A/T), SOD2 (Ala9Val), GPX1 (Pro198Leu), GSTM1 and GSTT1 polymorphisms in three Brazilian population groups: Kayabi Amerindians (n = 60), Kalunga Afro-descendants (n = 72), and an urban mixed population from Federal District (n = 162). Frequencies of the variants observed in Kalunga (18% to 58%) and Federal District (33% to 63%) were similar to those observed in Euro and Afro-descendants, while in Kayabi (3% to 68%), depending on the marker, frequencies were similar to the ones found in different ethnic groups. Except for SOD2 in all population groups studied here, and for GPX1 in Kalunga, the genotypic distributions were in accordance with Hardy-Weinberg Equilibrium. These data can clarify the contribution of different ethnicities in the formation of mixed populations, such as that of Brazil. Moreover, outcomes will be valuable resources for future functional studies and for genetic studies in specific populations. If these studies are designed to comprehensively explore the role of these genetic polymorphisms in the etiology of human diseases they may help to prevent inconsistent genotype-phenotype associations in pharmacogenetic studies

Distribution of glutathione S-transferase GSTM1 and GSTT1 null phenotypes in Brazilian Amerindians

The distribution of glutathione S-transferase (GST) GSTM1 and GSTT1 null phenotype frequencies in two Brazilian Amerindian tribes, the Munduruku tribe from Missão Cururu village (79 individuals) and the Kayabi tribe (41 individuals), was analyzed by polymerase chain reaction (PCR) amplification. The GST null phenotype frequencies for the Munduruku sample were 0% for GSTM1 and 27% for GSTT1 while for the Kayabi sample the null phenotype frequencies were 27% for GSTM1 and 29% for GSTT1. This is the first report of the absence of the GSTM1 null phenotype in any ethnic group

Haptoglobin gene subtypes in three Brazilian population groups of different ethnicities

Haptoglobin is a plasma hemoglobin-binding protein that limits iron loss during normal erythrocyte turnover and hemolysis, thereby preventing oxidative damage mediated by iron excess in the circulation. Haptoglobin polymorphism in humans, characterized by the Hp*1 and Hp*2 alleles, results in distinct phenotypes known as Hp1-1, Hp2-1 and Hp2-2, whose frequencies vary according to the ethnic origin of the population. The Hp*1 allele has two subtypes, Hp*1F and Hp*1S, that also vary in their frequencies among populations worldwide. In this work, we examined the distribution frequencies of haptoglobin subtypes in three Brazilian population groups of different ethnicities. The haptoglobin genotypes of Kayabi Amerindians (n = 56), Kalunga Afro-descendants (n = 70) and an urban population (n = 132) were determined by allele-specific PCR. The Hp*1F allele frequency was highest in Kalunga (29.3%) and lowest in Kayabi (2.6%). The Hp*1F/Hp*1S allele frequency ratios were 0.6, 1.0 and 0.26 for the Kayabi, Kalunga and urban populations, respectively. This variation was attributable largely to the Hp*1F allele. However, despite the large variation in Hp*1F frequencies, results of FST (0.0291) indicated slight genetic differentiation among subpopulations of the general Brazilian population studied here. This is the first Brazilian report of variations in the Hp *1F and Hp*1S frequencies among non-Amerindian Brazilians

Análise da variação de marcadores genéticos associados ao estresse oxidativo em grupos populacionais brasileiros

Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2010.A superóxido dismutase (SOD), a catalase (CAT), a haptoglobina (HAPTO), as glutationas S-Transferases (M1 e T1) e a glutationa peroxidase (GPX1) são marcadores genéticos associados ao estresse oxidativo, que têm como função inibir ou diminuir as taxas de oxidação no organismo, evitando danos ao DNA. A variação genética dessas enzimas sugere diferenças individuais quanto ao grau de proteção antioxidante e a distribuição das frequências alélicas apresenta diferenças geográficas, dependendo do grupo étnico. Neste trabalho foi descrita a distribuição da freqüência dos polimorfismos: CAT (21A/T), SOD2 (Ala9Val), GPX1 (Pro198Leu), subtipos da HAPTO e deleção dos genes da GSTM1 e GSTT1 em três grupos populacionais brasileiros de origens étnicas diferentes: Kayabi (n = 60), Kalunga (n = 72) e Distrito Federal (n = 162). A maioria das freqüências dos alelos variantes observadas em Kalunga (18% a 60%) e Distrito Federal (15% a 63%) foram similares aos observados em Euro e Afro-descendentes, enquanto que em Kayabi (3% a 68%), dependendo do marcador foram semelhantes aos Asiáticos, Ameríndios e Euro-descendentes. Exceto para SOD2 e HAPTO em todos os grupos de população estudados e para GPX1 em Kayabi e Kalunga, as distribuições genotípicas estavam de acordo com o equilíbrio de Hardy-Weinberg. Valores de FST mostram que há uma diferenciação genética moderada nestes três grupos populacionais brasileiros. Em populações miscigenadas, como a brasileira, esses dados podem elucidar a contribuição de diferentes etnias em sua formação. Além disso, estes polimorfismos têm revelado dados interessantes para evitar associações genótipo-fenótipo inconsistentes nos estudos de farmacogenética. _________________________________________________________________________________ ABSTRACTGenetic markers associated with oxidative stress such as superoxide dismutase (SOD), catalase (CAT), haptoglobin (HAPTER), glutathione S-transferase (M1 and T1) and glutathione peroxidase (GPX1) inhibit, or decrease the rate of oxidation in the organism avoiding damage to DNA. Genetic variation of these enzymes suggests individual differences in the degree of antioxidant protection and the distribution of allele frequencies shows geographical differences, depending on the ethnic group. This study describes the frequency distribution of polymorphisms CAT (21A/T), SOD2 (Ala9Val), GPX1 (Pro198Leu), HAPTO subtypes and deletions of the GSTM1 and GSTT1 in three population groups from different ethnic backgrounds: Kayabi (n = 60), Kalunga (n = 72) and the Federal District (n = 162). Most of the frequencies of variant alleles observed in Kalunga (18% to 60%) and the Federal District (15% to 63%) were similar to those observed in European and African descendants, while in Kayabi (3% to 68%) depending on the marker were similar to Asians, Amerindians and Euro-descendants. Except for SOD2 in all population groups studied and HAPTO in Kayabi and Federal Districti and GPX1 in Kalunga, the genotypic distributions were in accordance with the Hardy-Weinberg. FST values show that there is a moderate genetic differentiation in these three population groups. In admixed populations such as Brazilian, these data can elucidate the contribution of different ethnic groups in their formation. Moreover, these polymorphisms have revealed interesting data to avoid the genotype-phenotype inconsistent in pharmacogenetic studies

Glutathione S-Transferase M1 and T1 Polymorphisms in Brazilian African Descendants

The glutathione S-transferase gene family has an important role in the biotransformation and detoxification of different xenobiotics and endogenous compounds. Two polymorphic genes of this family, GSTM1 and GSTT1, present null alleles that consequently do not produce the respective enzyme when the genotype is homozygous. These polymorphisms are also interesting for population dynamics studies because they have great frequency variations among different ethnic groups and have been reported worldwide. The distribution of these alleles in urban and Amerindian populations in Brazil has been described, but none of those studies reported on African-descended rural populations. The aim of this study was to analyze the genotype frequency distribution of the GSTM1 and GSTT1 null alleles in an urban sample from the Federal District (n = 91) and in four semi-isolated African-descended populations: Mocambo (n = 55), Rio das Rãs (n = 117), Riacho de Sacutiaba (n = 34), and Kalunga (n = 68). The GSTM1 and GSTT1 null genotype frequencies in these populations range from 17% to 35% for GSTM1 and from 22% to 44% for GSTT1. These values are similar to those described in other African and African-descended populations. Despite this range, there is no distribution difference among the analyzed populations. Combined GSTM1 and GSTT1 null genotype frequencies range from 6% to 13% and are similar to Europeanderived populations, suggesting admixture with this ethnic group. This can be interpreted as a European contribution to these African-descended populations. Regarding the urban population in the Federal District, our results suggest an important African and European contribution