👤 Mara H Hutz

Hypertriglyceridemia is an important independent risk factor for coronary artery diseases and is determined by a wide range of factors, both genetic and exogenous. The A5 apolipoprotein, which is associated with the synthesis and removal of triglycerides (TG), is encoded by the APOA5 gene. One of the polymorphisms of this gene that has been the focus of a large number of studies, and which appears to be associated with increased TG, is S19W (rs 3135506). In this study, we examined the influence of this single nucleotide polymorphism (SNP) on TG levels of a sample of southern Brazilians. Samples obtained from 567 people of European descent were genotyped; interactions between this variant and anthropometric variables were analyzed, and the effects of lifestyle, sex, menopause, and variations of the APOE gene were evaluated. We found that the 19W allele is associated with increased TG (p = 0.025) and that this influence was modulated by sex (p = 0.003), menopause (p = 0.022) and the presence of the E*4 allele (p = 0.027). Our data showed, for the first time, the importance and magnitude of the influence of the S19W variant in a southern Brazilian population. Show less

APOC3 polymorphisms were associated with lipid parameters and coronary artery disease in several populations but not all. Considering the multifactorial inheritance and environmental factors that underlie the determination of triglyceride (TG) and HDL-C levels, the aims of the present study were to perform association analyses of APOC3 polymorphisms and these lipids in a southern Brazilian population of European descent to investigate possible interactions with other genetic and/or environmental factors. Six hundred and seventy-three subjects participated in the study. -482C>T, -455T>C and 3238C>G polymorphisms genotyping were carried out by PCR followed by restriction enzyme digestion. In female subjects the APOC3-APOE genotype combinations had a significant effect on triglyceride levels (ANOVA, P=0.009). Post hoc analysis showed that the observed differences were between APOC3 S(*)2 carriers and S(*)1S(*)1 homozygotes in individuals with an APOE(*)3/3 genotype (Tukey HSD post hoc test, P=0.027). In APOE(*)3/(*)3 subjects, the raising effect of APOC3 S(*)2 allele on TG concentrations was more pronounced in female smokers (+59.4%) than in nonsmokers (+18.8%, P of S(*)2-smoking interaction=0.009). Among APOE(*)3/(*)3 subjects, male carriers of the less common alleles -482T and -455C had significant lower levels of HDL-C compared to homozygotes -482C/C and -455T/T (P=0.02 and P=0.006, respectively). APOC3 polymorphisms were associated with lipid variables, but the magnitude of these associations was modulated by additional genetic, biologic and/or environmental factors. Show less

Genetic studies have suggested that polymorphisms of genes coding for apolipoproteins are significant determinants of serum lipoprotein and lipid levels in adults. However, only a few studies have investigated the association of these polymorphisms in children. Therefore, in the present investigation we studied the distribution of APOA1 -75 G>A, +83 C>T, APOC3 -482 C>T, -455 T>C and 3238 C>G, and APOA4 Q360H and T347S polymorphisms and their influence on plasma lipoprotein levels in children from a Brazilian northeastern admixed population. The seven polymorphic sites were genotyped in 414 children aged 5 to 15 years (mean 8.9 +/- 2.9). The genotypes of the seven polymorphic sites were assessed by PCR-RFLP methods. The frequencies of the less common alleles were, in general, intermediate among parental populations, as expected. Strong linkage disequilibrium was detected between polymorphisms at the APOA1, APOC3 and APOA4 loci in this admixed population sample. Overall the genotype effects seen in adults were weaker or absent in children. The APOC3/-455 and APOA4 T347S variants showed significant effects on HDL cholesterol in girls (P = 0.033 and P = 0.016, respectively). Significantly higher plasma total (P = 0.003) and LDL cholesterol (P = 0.004) levels were observed in boys who were carriers of the 3238G allele at the APOC3/3238 C>G site. These results disclosed an overall absence of associations between these polymorphisms and lipids in children. This finding is not unexpected because expression of the effect of these polymorphisms might depend on the interaction with environmental variables both internal and external to the individual. Show less

To investigate associations and gene-environment interactions of APOA-IV gene polymorphisms with obesity-related phenotypes in a Brazilian population. A total of 391 individuals (171 men and 220 women) were genotyped for Xbal, Thr347Ser and Gln360His polymorphisms by PCR-RFLP methods. Adjusted body mass index (BMI) and waist circumference (WC) were compared among genotypes/haplotypes by unpaired t-test or analysis of variance. Gene-environment interactions were tested by analysis of variance using a general linear model. Analysis of the APOA-IV gene variants separately showed that X*2 and 347Ser alleles were associated with higher BMI (P=0.02 for both polymorphisms). Haplotype analysis confirmed this association. For these polymorphisms, the effect on BMI appeared to depend on smoking status (test for interaction, P=0.007 and 0.02, respectively), the Thr347Ser variant was associated with a BMI increase in smokers only (P=0.002). At the single-locus level no association was observed between 360His allele and BMI; however, haplotype analyses showed an association of this gene variant and higher BMI. A trend for association with WC (P=0.05) was observed in male carriers of the 360His allele. The effect of this polymorphism also depended on smoking status (test for interaction, P=0.018). Nonsmoker male carriers of the 360His allele had a larger waist circumference than homozygotes for the Gln allele (P=0.003). Our data suggest that the APOA-IV gene polymorphisms investigated are associated with obesity-related traits. The effects of X*2 and 347Ser variants on BMI and the 360His variant on waist circumference depended on smoking status. Show less