Participants’ ages were in the range of 30-50 years old. Mean of age in the case group was 41.5±4.9 years and mean of age in the control group was 42.5±6.6 years with no significant difference (P=0.197). Gender (P=0.876) and smoking (P=0.323) in case and control groups had no significant differences.

Results of study showed that 70% (70 people) of the case group had a family history of CAD and 91% of the control group had no family history of CAD. There was a noticeable difference between case and control group (P=0.000) that clarifies the obvious role of family history in occurrence of CAD. In the case group 25% of participants had hypertension (HTN), 23% had hyperlipidaemia (HLP) and 25% had diabetes mellitus (DM). There were significant differences between groups in cardiovascular risk factors: HTN (0.001), HLP (0.07), DM (0.010) (Table 1).

Table 1. Demographic data of both study groups

FHX: family history of CAD, DM: diabetes mellitus, HLP: hyperlipidaemia, HTN: hypertension

According to the results of study there was no significant difference between CC genotype mutant of TLR-4 gene and occurrence of premature CAD (p value: 0.435) but in mix genotype CC+TC vs TT there was a significant difference between premature CAD and healthy subjects (p value: 0.021), and C-allele frequency distributions were not significantly different (P;0.093) (Table 2).
Difference between alleles of TLR-4 gene (C and T) and occurrence of
premature CAD in case and control groups is shown in Table 2 (p value: 0.013).

Table 2: Frequencies of genotypes and alleles in participants

DISCUSSION

MI is the leading cause of mortality in developed countries and the second leading cause in developing countries (1). Expression of different inflammatory genes, specifically TLR4, has increased significantly in human atherosclerotic plaques (18). 1927911 SNP located on chromosome 9 is one the polymorphisms that has always been investigated in CVDs (19).

According to the results found in this study, distribution of heterozygous genotype (TC) was meaningfully higher than that in the healthy group control but the mutated homozygous genotype did not show a meaningful difference. Besides that, when compared to TC state, the genotype carrying the mutated allele (TC+CC) did not show a meaningful difference.

Even though the distribution of the mutated C allele was higher in the healthy control group compared to the premature MI group, this difference was not meaningful.

The Logistic regression analysis of distribution of genotype in rs1927911 in both genders shows that there is no meaningful concomitance in men and women, even though the mutated C allele was meaningfully more in females than in males.

Results of a study conducted by Yanmin Song et al. in the southern Chinese province of Hunan in 2014 showed that for rs1927911 there is a meaningful difference between acute cardiac ischemia (ACI) patients and the control groups from a genotype and allele distribution but hypertension, fasting blood sugar and serum fat level with different genotypes in both ACI patients and control groups had no meaningful difference (20).

In a study done by Daniel A. Enquobahrie et al. sweeping changes of gene in PPARA (peroxisome proliferator activated receptor alpha) and TLR4 gene was accompanied by MI. A minor allele of PPARA SNP, rs4253623, was accompanied with an increased risk of MI and a minor allele of TLR4 SNP, rs1927911, with an increased risk of MI. rs1927911 minor allele, a part of TLR4-D haplotype, is accompanied with a 12% risk of MI (21).

CONCLUSION

According to the findings of this study, it seems like the presence of the carrying genotype of mutated allele (TC+CC) in rs1927911 single nucleotide polymorphism (SNP) of TLR4 gene is associated with an increase of premature MI.

Considering the breadth of polymorphisms of TLR4 gene and role of genetics in premature MI, in order to establish this polymorphism as a risk factor, further studies in larger populations in this area is proposed.

Acknowledgement
The present study supported by Deputy of research, Jahrom University of Medical Sciences.