Polimorfismo genético de la apolipoproteína E en un grupo de escolares del centro-oriente colombiano: comparación con las concentraciones plasmáticas de lípidos y apolipoproteínas

Polymorphisms of apolipoprotein E in the Afro-descendant population of Buenaventura, Colombia

OBJETIVES

To estimate the frequency distribution, both allelic and genotypic, of the APOE gene in the Afro-descendant population of Buenaventura, Colombia.

METHODS

Three hundred and forty-eight Afro-descendant individuals were analysed and the APOE locus was genotyped by PCR-RFLP. The allelic and genotypic frequencies were established by direct counting and the Hardy-Weinberg equilibrium was evaluated through χ² test. The frequencies obtained in this study were compared with frequencies reported for other Colombian populations through the Fisher's exact test.

RESULTS

The following allelic frequencies were observed: E3, 70.8%; E4, 21.4%, and E2, 7.8%. The genotypic frequencies were: E3/E3, 51.1%; E3/E4, 27.3%; E2/E3, 12.1%; E4/E4, 6%; E2/E4, 3.5%, and E2/E2, 0%. The entire examined population was found in Hardy-Weinberg equilibrium (P=.074), and significant differences were found in the allele E4 when comparing this population with the Amerindian and mestizo populations of Bogotá, Quindío, Centro-Oriente, Valle del Cauca, Barranquilla and Medellín (P≤ 0.0345).

CONCLUSIONS

The allelic frequencies observed in this study were significantly different from the frequencies reported in other Colombian populations. The high representativeness of the E4 and E2 alleles validates the hypothesis that there are micro-evolutionary processes that have been acting on their frequencies and could be associated with susceptibility to neuropsychiatric diseases such as Alzheimer's disease, metabolic alterations of fats and/or coronary artery disease.

Polymorphisms of apolipoprotein E in the Afro-descendant population of Buenaventura, Colombia

OBJETIVES

To estimate the frequency distribution, both allelic and genotypic, of the APOE gene in the Afro-descendant population of Buenaventura, Colombia.

METHODS

Three hundred and forty-eight Afro-descendant individuals were analysed and the APOE locus was genotyped by PCR-RFLP. The allelic and genotypic frequencies were established by direct counting and the Hardy-Weinberg equilibrium was evaluated through χ2 test. The frequencies obtained in this study were compared with frequencies reported for other Colombian populations through the Fisher's exact test.

RESULTS

The following allelic frequencies were observed: E3, 70.8%; E4, 21.4%, and E2, 7.8%. The genotypic frequencies were: E3/E3, 51.1%; E3/E4, 27.3%; E2/E3, 12.1%; E4/E4, 6%; E2/E4, 3.5%, and E2/E2, 0%. The entire examined population was found in Hardy-Weinberg equilibrium (P=.074), and significant differences were found in the allele E4 when comparing this population with the Amerindian and mestizo populations of Bogotá, Quindío, Centro-Oriente, Valle del Cauca, Barranquilla and Medellín (P≤ 0.0345).

CONCLUSIONS

The allelic frequencies observed in this study were significantly different from the frequencies reported in other Colombian populations. The high representativeness of the E4 and E2 alleles validates the hypothesis that there are micro-evolutionary processes that have been acting on their frequencies and could be associated with susceptibility to neuropsychiatric diseases such as Alzheimer's disease, metabolic alterations of fats and/or coronary artery disease.

APOE gene polymorphism analysis in Barranquilla, Colombia

INTRODUCTION

The genetic variability present in the APOE gene polymorphism is considered an important factor associated with predisposition to diseases affecting lipid metabolism, as well as heart diseases and Alzheimer's disease, among others. Understanding it as a risk factor in different populations and ethnic groups is a useful tool. 

OBJECTIVE

To analyze the APOE gene polymorphism and determine allelic and genotypic frequencies of a representative sample of population from Barranquilla, Colombia. 

MATERIALS AND METHODS

We performed a descriptive and comparative study. The sample size was 227 unrelated individuals from Barranquilla, Colombia. 

RESULTS

The most frequent allele was the ε3, with 85%, followed by the ε4 allele (13%) and ε2 (1.8%). The genotypes found were: ε3/ε3: 71.8%, ε3/ε4: 24.2%, ε2/ε3: 2.2%, ε2/ε4: 1.3% and ε4/ε4: 0.4%. The ε2/ε2 genotype was not found in this study. The sample exhibited the Hardy-Weinberg equilibrium. 

CONCLUSION

The frequency of the ε3 allele and the ε3/ε3 genotype was similar to that reported in the literature in countries like Brazil, Mexico, Colombia, and in some Colombian Amerindian ethnic groups. The ε2/ε2 genotype was absent. This result is consistent with those found in other population groups worldwide. The frequency of the ε4 allele and the genotypes associated in this population could be related to the presence of diseases such as hypercholesterolemia, myocardial infarction and Alzheimer.

[Prevalence of Variants in the Apolipoprotein E (APOE) Gene in a General Population of Adults from an Urban Area of Medellin (Antioquia)]

OBJECTIVE

To determine the allelic and genotype frequencies of apolipoproteine E (APOE) gene in a representative sample of the adult population of Medellin in 2010.

METHODS

A representative sample of the adult population of Medellin, was obtained by means of a multi-stage, stratified, conglomerate based sampling method. APOE genotyping was carried out on each of the participants. The sampling design was taken into consideration for the frequencies and association analysis.

RESULTS

The frequencies of the APOE alleles E2, E3 and E4 were 3.9, 92.0 and 4.1%, respectively. The frequencies of the different APOE genotypes were as follows: 2/2, 0.2%; 2/3, 6.8%; 2/4, 0.6%; 3/3, 85.0%; 3/4, 7.2%, and 4/4, 0.3%.

CONCLUSIONS

The allelic and genotype frequencies of APOE in an adult population of Medellin did not differ substantially from other series reported in South America. These data are important to determine the real impact of APOE on the population risk of several psychiatric diseases.

Apolipoprotein A5-1131T>C polymorphism, but not APOE genotypes, increases susceptibility for dyslipidemia in children and adolescents

Apolipoprotein A5 (APOA5) and apolipoprotein E (APOE) play important roles in the metabolism of cholesterol and triglycerides. The aim of this study was to determine the allelic and genotypic distributions of the APOA5-1131T>C (rs 662799) and the APOE HhaI polymorphisms and to identify the association of both individual and combined APOA5-APOE genetic variants and the risk for dyslipidemia in children and adolescents. We genotyped 53 dyslipidemic and 77 normolipidemic individuals. The total cholesterol, triglycerides and HDL cholesterol were determined enzymatically. For APOA5 polymorphism, the presence of the allele C confers an individual risk for dyslipidemia (OR = 2.38, 95% CI = 1.15-4.89; P = 0.018). No significant differences were observed for lipid parameters among the APOA5 groups, except for a higher value of HDLc (P = 0.024) in C-carriers. The allelic and genotypic frequencies of APOE polymorphism were similar between groups and did not increase the susceptibility for dyslipidemia. None of the combined APOA5-APOE polymorphisms increased risk for dyslipidemia. We demonstrated an association between APOA5-1131T>C polymorphism and dyslipidemia in children and adolescents. This finding may be useful to guide new studies with genetic markers down a path toward a better characterization of the genetic risk factors for dyslipidemia and atherosclerotic diseases.

Genetic and environmental influences on serum lipid tracking: a population-based, longitudinal Chinese twin study

We conducted cross-sectional and longitudinal twin analysis to explore genetic and environmental contribution to serum lipid tracking during childhood and adolescence. The study sample was part of a population-based twin cohort that was recruited in the rural areas of the Anhui Province of China. The baseline recruitment of twins was carried out from 1998 through 2000 and the follow-up from 2005 through 2007. Serum lipids showed significant tracking during childhood and adolescence. Participants with lipids at the highest tertile at the baseline tended to remain high at follow-up across ages and Tanner stages, whereas subjects with lipids at the lowest tertile at the baseline tended to remain low at follow-up. Using twin modeling, we showed that genetic and environmental factors contributed to individual variations in lipid levels and tracking from the baseline to the follow-up visit. The estimated tracking correlations for total cholesterol, triglyceride, and LDL cholesterol were in the range of 0.25-0.53 and were predominantly influenced by genetic factors. In contrast, the phenotypic tracking of HDL cholesterol was influenced by both genetic and environmental factors. Our study underscores the importance of considering both environmental and genetic factors in studying the etiology of dyslipidemia.

Genetic influences on blood lipids and cardiovascular disease risk: tools for primary prevention

Genetic polymorphism in human populations is part of the evolutionary process that results from the interaction between the environment and the human genome. Recent changes in diet have upset this equilibrium, potentially influencing the risk of most common morbidities such as cardiovascular diseases, obesity, diabetes, and cancer. Reduction of these conditions is a major public health concern, and such a reduction could be achieved by improving our ability to detect disease predisposition early in life and by providing more personalized behavioral recommendations for successful primary prevention. In terms of cardiovascular diseases, polymorphisms at multiple genes have been associated with differential effects in terms of lipid metabolism; however, the connection with cardiovascular disease has been more elusive, and considerable heterogeneity exists among studies regarding the predictive value of genetic markers. This may be because of experimental limitations, the intrinsic complexity of the phenotypes, and the aforementioned interactions with environmental factors. The integration of genetic and environmental complexity into current and future research will drive the field toward the implementation of clinical tools aimed at providing dietary advice optimized for the individual's genome. This may imply that dietary changes are implemented early in life to gain maximum benefit. However, it is important to highlight that most reported studies have focused on adult populations and to extrapolate these findings to children and adolescents may not be justified until proper studies have been carried out in these populations and until the ethical and legal issues associated with this new field are adequately addressed.