Browsing by Author "Santos, Cristina"
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- Cross-sectional study of risk factors for atherosclerosis in the Azorean populationPublication . Cymbron, Teresa; Raposo, Mafalda; Kazachkova, Nadia; Bettencourt, Conceição; Silva, Francisca; Santos, Cristina; Dahmani, Yahya; Lourenço, Paula C.; Ferin, Rita; Pavão, Maria Leonor; Lima, ManuelaBackground: Atherosclerosis -a major cause of vascular disease, including ischemic heart disease (IHD), is a pathology that has a two-fold higher mortality rate in the Azorean Islands compared to mainland Portugal. Aim: This cross-sectional study investigated the role of genetic variation in the prevalence of atherosclerosis in this population. Subjects and methods: A total of 305 individuals were characterized for polymorphisms in eight susceptibility genes for atherosclerosis: ACE, PAI1, NOS3, LTA, FGB, ITGB3, PON1 and APOE. Data were analysed with respect to phenotypic characteristics such as blood pressure, lipid profile, life-style risk factors and familial history of myocardial infarction. Results: In the total sample, frequencies for hypercholestrolemic, hypertensive and obese individuals were 63.6%, 39.3% and 23.3%, respectively. The genetic profile was similar to that observed in other European populations, namely in mainland Portugal. No over-representation of risk alleles was evidenced in this sample. Conclusions: One has to consider the possibility of an important non-genetic influence on the high cholesterolemia present in the Azorean population. Since diet is the most important life-style risk factor for dyslipidemia, studies aiming to evaluate the dietary characteristics of this population and its impact on serum lipid levels will be of major importance.
- Polymorphism of the APOE locus in the Azores Islands (Portugal)Publication . Bettencourt, Conceição; Montiel, Rafael; Santos, Cristina; Pavão, Maria Leonor; Viegas-Crespo, Ana Maria; Lopes, Paula Alexandra; Lima, ManuelaOur aim in this study is to report on the polymorphism of the APOE gene in the Azores Islands (Portugal) to obtain a population baseline of the existing variation in this locus, known to be one of the genetic determinants of plasma lipid levels. One hundred twenty-six Azorean individuals were typed for the APOE polymorphism using standard PCR-RFLP. Allele frequencies obtained for APOE*2, APOE*3, and APOE*4 were 6.75%, 83.73%, and 9.52%, respectively. The APOE*3/*3 genotype presented the highest frequency (69.84%), and the APOE*4/*4 genotype had the lowest frequency (0.79%). Genotype frequencies were in conformity with Hardy-Weinberg expectations. The observed genotype and allele frequencies were similar to those reported for other Iberian samples. Furthermore, Nei's gene diversity ((H) over cap = 0.2864 +/- 0.0351) was similar to that reported for samples from mainland Portugal. The data generated from this study will be of importance in the context of ongoing studies concerning the factors that influence lipid levels in the Azorean population.
- Polymorphism of the ApoE locus in the Azores Islands (Portugal)Publication . Bettencourt, Conceição; Montiel, Rafael; Santos, Cristina; Pavão, Maria Leonor; Viegas-Crespo, Ana Maria; Lopes, Paula Alexandra; Lima, ManuelaThe aim of this work was to report on the polymorphism of the ApoE locus in the Azores Islands (Portugal) in order to get insights on the genetic background that influences the lipid profile in this population, ascertained as considerably high in a preliminary study of a sample of healthy subjects (60% of individuals were hypercholesterolemics). One hundred and twenty six Azorean individuals were typed for ApoE polymorphism using standard PCR-RFLP. The allelic frequencies obtained for ε2, ε3 and ε4 were 6.75%, 83.73% and 9.52%, respectively. Genotypic frequencies were in conformity with Hardy-Weinberg expectations. The ε3/ε3 genotype presented the highest frequency (69.84%), whilst ε4/ε4 was the least frequent (0.79%). The genotypic and allelic frequencies observed were similar to those reported for other Iberian samples. Furthermore, Nei’s gene diversity (0.2864±0.0351) was similar to the reported for samples from Mainland Portugal. Results obtained did not evidence a particular behaviour of the ApoE locus that could be directly related with the high levels of total cholesterol determined in the Azorean population.
- Relationship of the APOE polymorphism and lipid profile: A population-based study in the Azores Islands (Portugal)Publication . Raposo, Mafalda; Dahmani, Yahya; Silva, Francisca; Tavares, M.; Cymbron, Teresa; Santos, Cristina; Bettencourt, Conceição; Ferin, Rita; Correia, Cristina; Pavão, Maria Leonor; Lima, ManuelaThe factors leading to a two-fold mortality rate from coronary artery disease (CAD) in the Azores, as compared to Mainland Portugal, have not been elucidated. Previous studies reported a population tendency for hypercholesterolemia, one of the main factors contributing to the development of atherosclerosis (AT), considered the primary cause of CAD. Apolipoprotein E has a key role in plasma lipid metabolism, given its function as a ligand for cell-surface receptor mediated uptake of lipoproteins. Polymorphism in the apolipoprotein gene (APOE) results in three major isoforms encoded by three codominant alleles (E2, E3 and E4). With the purpose of establishing the pattern of variation at the APOE locus and determining its association with lipid profile, we studied a random sample of 298 unrelated, apparently healthy individuals of Azorean origin. In nearly 50% of the sample total cholesterol (TC) was above 200mg/dl; in 25% of the individuals LDL-cholesterol (LDL-C) was higher than 130 mg/dl. Allele frequencies were 0.0833, 0.8317 and 0.0850 for E2, E3 and E4, respectively. Genotype frequencies were higher for E3*E3 genotype (66.1%); genotype distribution displayed conformity with Hardy-Weinberg expectations. No differences in allelic frequencies were found in comparison with other Caucasian populations, namely with mainland Portugal. E3*E4 individuals presented the highest cholesterol levels. Analysis of variance performed with the most represented genotypes (E2*E3, E3*E3 and E3*E4) revealed a clear association between the genotypic composition and TC, as well as LDL-C, thus confirming in this population, the role of APOE as one of the genetic determinants of AT.