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XbaI polymorphism in DNA at the apolipoprotein B locus is associated with myocardial infarction (MI)
1Institute of Medical Genetics, University of Oslo, Norway.
Insights
The XbaI polymorphism in apolipoprotein B (apoB) gene is linked to myocardial infarction (MI) risk. Individuals with the X-X- genotype have a significantly higher risk of MI, even after adjusting for lipid levels.
Area of Science:
- Cardiovascular Genetics
- Molecular Biology
- Epidemiology
Background:
- High levels of low-density lipoprotein (LDL) and apolipoprotein B (apoB) are established risk factors for atherosclerosis and myocardial infarction (MI).
- Genetic variations, particularly DNA polymorphisms in the apoB gene, influence population levels of LDL and apoB, and may affect susceptibility to cardiovascular diseases.
Purpose of the Study:
- To investigate the association between the XbaI polymorphism at the apoB locus and the risk of myocardial infarction (MI).
Main Methods:
- A case-control study was conducted with 238 MI survivors and 621 controls.
- Genotyping for the XbaI polymorphism (a silent nucleotide substitution) in the apoB gene was performed.
- Statistical analyses, including univariate and multivariate logistic regression, were used to assess genotype frequencies and odds ratios, adjusting for relevant clinical and biochemical factors.
Main Results:
- Univariate analysis showed no significant difference in genotype frequencies between MI patients and controls.
- Multivariate logistic regression revealed that X-X- homozygotes had a 2.16-fold increased odds of having MI compared to heterozygotes and X+X+ homozygotes (p = 0.007).
- This increased risk associated with the X-X- genotype was observed across subgroups stratified by levels of apoB, HDL cholesterol, and Lp(a) lipoprotein.
Conclusions:
- The X-X- genotype of the XbaI polymorphism in the apoB gene is a significant risk factor for myocardial infarction.
- This genetic risk appears independent of, or modulated by, established lipid risk factors like apoB and HDL cholesterol levels.
Abstract:
High levels of low density lipoprotein (LDL) and its apolipoprotein B (apoB) are risk factors for atherosclerosis and myocardial infarction (MI). There is rich genetic polymorphism in apoB, first detected as the Ag allotypes of LDL, but today mostly examined at the DNA level. Genes contribute to the population variation in LDL and apoB levels and alleles in polymorphisms at the apoB locus are candidate genes with respect to control of lipid levels and susceptibility to atherosclerosis and MI. The XbaI polymorphism at the apoB locus, which involves the third base of threonin codon 2488 (ACC-->ACT) without changing the amino acid sequence was examined in a case-control study comprising 238 survivors of myocardial infarction (MI) and 621 controls. In univariate analysis, frequencies of genotypes in this polymorphism were not statistically different between patients and controls of either sex. However, in multivariate logistic regression analysis, the odds ratio X-X- homozygotes (homozygotes for absence of restriction site) for having MI compared to the pooled group of heterozygotes and X+X+homozygotes (homozygotes for presence of restriction site) was 2.16 (p = 0.007), after adjustments for age, sex, and levels of apoB, high density lipoprotein (HDL) cholesterol (HDLC) and Lp(a) lipoprotein. It appeared that heterozygotes do not have increased risk, compared to the X+X+ homozygotes. Stratification according to low or high levels of apoB, HDLC and Lp(a) lipoprotein, showed that the X-X- genotype was more common in patients than controls, in all subgroups.(ABSTRACT TRUNCATED AT 250 WORDS)