Association of the insertion/deletion gene polymorphism of the apolipoprotein B signal peptide with myocardial infarction in Tunisian patients.
BACKGROUND
Numerous polymorphisms of the apolipoprotein B (APOB) gene have been described. Particularly, the insertion/deletion (Ins/Del) polymorphism located in the coding part of the signal peptide of apoB, associated with modification of lipid concentrations and the risk of coronary artery disease and/or myocardial infarction (MI), has been reported in the general population. Moreover, conflicting results emerge from the literature and suggest that the effect is context-dependent. In the present study, the first investigation of the Ins/Del polymorphism of the APOB gene in Tunisian patients with MI, we examined a possible association between this polymorphism and MI in a subgroup of the Tunisian population.


METHODS
A total of 318 Tunisian patients with MI and 368 healthy controls were included in the study. Genomic DNA was extracted from white blood cells, and the Ins/Del polymorphism was determined by electrophoresis in polyacrylamide gels after PCR amplification. A binary logistic regression analysis was performed to test how the association between MI and Ins/Del polymorphism is independent from confounding factors.


RESULTS
A significant difference in genotype distribution and allele frequency was observed between patients and controls. Patients with MI had a frequency of 7.2% for the Del/Del genotype, 39.6% for the Ins/Del genotype, and 53.1% for the Ins/Ins genotype. Controls had a frequency of 3.0% for the Del/Del, 32.1% for the Ins/Del and 64.9% for the Ins/Ins genotype (chi2=12.93, p=0.002). The MI patient group showed a significantly higher frequency of the Del allele compared to controls (27.1% vs. 19.1%; chi2=12.50, p=0.0004). In comparison to the Ins/Ins homozygotes, the odds ratio (95% confidence interval) for MI was 1.51 (1.09-2.07) for Ins/Del heterozygotes and 2.95 (1.40-6.22) for Del/Del homozygotes. In multivariate analysis, age (p=0.001), smoking (p<0.001), hypertension (p=0.001), diabetes mellitus (p<0.001), and dyslipidemia (p=0.01) were independent correlates of the presence of MI, whereas the Ins/Del polymorphism (p=0.330) was not an independent predictor of MI.


CONCLUSIONS
The present study shows a significant but not independent association between the Ins/Del polymorphism of the APOB gene and MI in the Tunisian population.
Kallel
Amani
A
Department of Biochemistry, Research Laboratory LAB-SM-01, Hospital la Rabta, Tunis, Tunisia.
Ben Ali
Samir
S
Sediri
Yosra
Y
Chabrak
Sonia
S
Elasmi
Monia
M
Sanhaji
Haïfa
H
Souheil
Omar
O
Haj-Taieb
Sameh
S
Feki
Moncef
M
Mechmeche
Rachid
R
Jemaa
Riadh
R
Kaabachi
Naziha
N
D001055:Apolipoproteins B / Q000737:chemistry / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D054643:INDEL Mutation; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology / Q000235:genetics*; D011110:Polymorphism, Genetic; D021382:Protein Sorting Signals / Q000235:genetics*; D012044:Regression Analysis; D014416:Tunisia / Q000453:epidemiology
D001055:Apolipoproteins B; D021382:Protein Sorting Signals