Association of ApoE polymorphisms with prevalent hypertension in 1406 older adults: the Bambuí Health Aging Study (BHAS).

Apolipoprotein E (ApoE) polymorphism influences lipid metabolism, but its association with arterial hypertension is controversial. The objective of this study was to examine the association between ApoE polymorphism and prevalent hypertension in a large unselected population of older adults. Participants from the baseline of the Bambuí Health Aging Study whose ApoE genes had been genotyped were selected for this study (N = 1406, aged 60-95 years). These subjects represented 80.7% of the total elderly residents in Bambuí city, MG, Brazil. Hypertension was defined as a systolic blood pressure > or =140 mmHg and/or a diastolic blood pressure > or =90 mmHg, or the use of anti-hypertensive medication. The exposure variable was the ApoE genotype as follows: epsilon3 carriers, epsilon3epsilon3; epsilon2 carriers, epsilon2epsilon2 or epsilon2epsilon3, and epsilon4 carriers, epsilon3epsilon4 or epsilon4epsilon4. Potential confounding variables were age, gender, traditional cardiovascular risk factors, uric acid, and creatinine levels. The prevalence of hypertension was 61.3%. Compared with the epsilon3 homozygotes, neither the epsilon2 nor the epsilon4 carrier status was associated with hypertension (adjusted prevalence ratios = 0.94, 95%CI = 0.83-1.07 and 0.98, 0.89-1.07, respectively). On the other hand, the epsilon2 allele carriers had lower LDL cholesterol levels (P < 0.001) and the epsilon4 carriers had higher LDL cholesterol levels (P = 0.036). This study provides epidemiologic evidence that the ApoE genotype is not associated with prevalent hypertension in old age.

Association of ApoE polymorphisms with prevalent hypertension in 1406 older adults: the Bambuí Health Aging Study (BHAS)

Apolipoprotein E (ApoE) polymorphism influences lipid metabolism, but its association with arterial hypertension is controversial. The objective of this study was to examine the association between ApoE polymorphism and prevalent hypertension in a large unselected population of older adults. Participants from the baseline of the Bambuí Health Aging Study whose ApoE genes had been genotyped were selected for this study (N = 1406, aged 60-95 years). These subjects represented 80.7 percent of the total elderly residents in Bambuí city, MG, Brazil. Hypertension was defined as a systolic blood pressure ³140 mmHg and/or a diastolic blood pressure ³90 mmHg, or the use of anti-hypertensive medication. The exposure variable was the ApoE genotype as follows: e3 carriers, e3e3; e2 carriers, e2e2 or e2e3, and e4 carriers, e3e4 or e4e4. Potential confounding variables were age, gender, traditional cardiovascular risk factors, uric acid, and creatinine levels. The prevalence of hypertension was 61.3 percent. Compared with the e3 homozygotes, neither the e2 nor the e4 carrier status was associated with hypertension (adjusted prevalence ratios = 0.94, 95 percentCI = 0.83-1.07 and 0.98, 0.89-1.07, respectively). On the other hand, the e2 allele carriers had lower LDL cholesterol levels (P < 0.001) and the e4 carriers had higher LDL cholesterol levels (P = 0.036). This study provides epidemiologic evidence that the ApoE genotype is not associated with prevalent hypertension in old age.

Apolipoprotein E polymorphism distribution in an elderly Brazilian population: the Bambuí Health and Aging Study

Apolipoprotein E (ApoE) is one of the most extensively studied genes in the context of aging, but there are few population-based studies on ApoE polymorphism in the elderly in developing countries. The objective of the present study was to assess ApoE allele and genotype distribution in a large elderly community-based sample and its association with age, sex and skin color. Participants included 1408 subjects (80.8 percent of all residents aged ³60 years) residing in Bambuí city, MG, Brazil. The DNA samples were subjected to the polymerase chain reaction amplification, followed by the restriction fragment length polymorphism technique, with digestion by HhaI. Analysis was carried out taking into consideration the six ApoE genotypes (e3/e3, e3/e4, e2/e3, e4/e4, e2/e4, and e2/e2), the three ApoE alleles, and the number of ApoE4 alleles for each individual. The e3 allele predominated (80.0 percent), followed by e4 (13.5 percent) and e2 (6.5 percent). All six possible genotypes were observed, the e3/e3 genotype being the most frequent (63.4 percent). This distribution was similar to that described in other western populations. Sex was not associated with number of ApoE4 alleles. Black skin color was significantly and independently associated with the presence of two ApoE4 alleles (age-sex adjusted OR = 7.38; 95 percentCI = 1.93-28.25), showing that the African-Brazilian elderly have a high prevalence of the e4 allele, as observed in blacks from Africa. No association between number of ApoE4 alleles and age was found, suggesting the absence of association of ApoE genotype with mortality in this population.

Apolipoprotein E polymorphism distribution in an elderly Brazilian population: the Bambuí Health and Aging Study.

Apolipoprotein E (ApoE) is one of the most extensively studied genes in the context of aging, but there are few population-based studies on ApoE polymorphism in the elderly in developing countries. The objective of the present study was to assess ApoE allele and genotype distribution in a large elderly community-based sample and its association with age, sex and skin color. Participants included 1408 subjects (80.8% of all residents aged (3)60 years) residing in Bambuí city, MG, Brazil. The DNA samples were subjected to the polymerase chain reaction amplification, followed by the restriction fragment length polymorphism technique, with digestion by HhaI. Analysis was carried out taking into consideration the six ApoE genotypes (e3/e3, e3/e4, e2/e3, e4/e4, e2/e4, and e2/e2), the three ApoE alleles, and the number of ApoE4 alleles for each individual. The e3 allele predominated (80.0%), followed by e4 (13.5%) and e2 (6.5%). All six possible genotypes were observed, the e3/e3 genotype being the most frequent (63.4%). This distribution was similar to that described in other western populations. Sex was not associated with number of ApoE4 alleles. Black skin color was significantly and independently associated with the presence of two ApoE4 alleles (age-sex adjusted OR = 7.38; 95%CI = 1.93-28.25), showing that the African-Brazilian elderly have a high prevalence of the e4 allele, as observed in blacks from Africa. No association between number of ApoE4 alleles and age was found, suggesting the absence of association of ApoE genotype with mortality in this population.

Utilization of microsatellites for the analysis of genomic alterations in colorectal cancers in Brazil.

Two different pathogenetic mechanisms are proposed for colorectal cancers. One, the so-called "classic pathway", is the most common and depends on multiple additive mutational events (germline and/or somatic) in tumor suppressor genes and oncogenes, frequently involving chromosomal deletions in key genomic regions. Methodologically this pathway is recognizable by the phenomenon of loss of heterozygosity. On the other hand, the "mutator pathway" depends on early mutational loss of the mismatch repair system (germline and/or somatic) leading to accelerated accumulation of gene mutations in critical target genes and progression to malignancy. Methodologically this second pathway is recognizable by the phenomenon of microsatellite instability. The distinction between these pathways seems to be more than academic since there is evidence that the tumors emerging from the mutator pathway have a better prognosis. We report here a very simple methodology based on a set of tri-, tetra- and pentanucleotide repeat microsatellites allowing the simultaneous study of microsatellite instability and loss of heterozygosity which could allocate 70% of the colorectal tumors to the classic or the mutator pathway. The ease of execution of the methodology makes it suitable for routine clinical typing.

Utilization of microsatellites for the analysis of genomic alterations in colorectal cancers in Brazil

Two different pathogenetic mechanisms are proposed for colorectal cancers. One, the so-called "classic pathway", is the most common and depends on multiple additive mutational events (germline and/or somatic) in suppressor genes and oncogenes, frequently involving chromosomal deletions in key genomic regions. Methodologically this pathway is recognizable by the phenomenon of loss of heterozygosity. On the other hand, the "mutator pathway" depends on early mutational loss of the mismatch repair system (germline and/or somatic) leading to accelerated accumulation of gene mutations in critical target genes and progression to malignancy. Methodologically this second pathway is recognizable by the phenomenon of microsatellite instability. The distinction between these pathways seems to be more than academic since there is evidence that the tumors emerging from the mutator pathway have a better prognosis. We report here a very simple methodology based on a set of tri-, tetra-and pentanucleotide repeat microsatellites allowing the simultaneous study of microsatellite instability and loss of heterozygosity which could allocate 70 per cent of the colorectal tumors to the classic or the mutator pathway. The ease of execution of the methodology makes it suitable for routine clinical typing.

Simultaneous detection of size and sequence polymorphisms in the transcribed trinucleotide repeat D2S196E (EST00493).

Long expansions of transcribed trinucleotide microsatellites have been etiologically associated with some neurological diseases. The investigation of such novel polymorphisms has thus become a subject of great interest. We searched the expressed sequence tag databank for reiterated trinucleotides and selected EST00493 (D2S196E) with 14 tandem ACA triplets as a potentially polymorphic locus. Size variation was readily detected, with four common alleles containing 12-15 repeats. In addition, we observed distinct heteroduplexes in amplifications from individuals with identical ACA genotypes. Sequencing of their polymerase chain reaction (PCR) products revealed a G-->A transition immediately preceding the trinucleotide repeats, hence defining 8 distinct haplotypes and 36 possible genotypes. Indeed, mutation detection enhancement gel electrophoresis of mixed PCR products from cloned haplotypes revealed 24 distinct heteroduplex patterns for the six possible trinucleotide heterozygotes. The observation of heteroduplex patterns in non-denaturing polyacrylamide gel electrophoresis (instead of the more commonly used denaturing gels) can thus be utilized to increase the informativeness of microsatellite polymorphisms by unraveling otherwise cryptic sequence variation. The D2S196E polymorphism has proved useful for demonstrating microsatellite instability and loss of heterozygosity in colorectal tumors.