Exploring the causal pathway from omega-6 levels to coronary heart disease: A network Mendelian randomization study

https://doi.org/10.1016/j.numecd.2019.09.013Get rights and content
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Highlights

  • Evidence on the effect of omega-6 fats on coronary heart disease (CHD) risk remains inconclusive.

  • Omega-6 was positively causal associated with TC, LDL-C, and TG but was not associated with HDL-C.

  • Omega-6 was positively causal associated CHD, which might be partially mediated by TC, LDL-C, and TG.

Abstract

Background and aims

Evidence on the effect of omega-6 fats on coronary heart disease (CHD) risk remains inconclusive. We applied a network MR framework to determine the causal effects between omega-6 levels and CHD and the potential cholesterol metabolic risk factors (Total cholesterol, TC; Low-density lipoprotein cholesterol, LDL-C; High-density lipoprotein cholesterol, HDL-C; Triglycerides, TG) which might act as mediators in the link between omega-6 levels and CHD by integrating summary-level genome wide association study (GWAS) data.

Methods and results

Network MR analysis-an approach using genetic variants as the instrumental variables for both the exposure and mediator to infer causality was performed to examine the causal effects between omega-6 levels and CHD and cholesterol metabolic risk factors. Summary statistics from the Kettunen et al. ’s consortium were used (n = 13506) for omega-6, CARDIoGRAMplusC4D consortium data were used (n = 184305) for CHD, and GLGC consortia data were used (n = 108363) for TC, LDL-C, HDL-C, and TG. The IVW method estimate indicated that the odds ratio (OR) (95% confidence interval [CI]) for CHD was 1.210 (1.118–1.310) per standard deviation increase in omega-6. Results were consistent in MR Egger method (OR, 1.418; 95% CI, 1.087–1.851; P = 0.050) and weighted median methods (OR, 1.239; 95% CI, 1.125–1.364; P = 0.000). Omega-6 was positively causal associated with TC, LDL-C, and TG but was not associated with HDL-C. Moreover, TC, LDL-C, and TG were positively associated with CHD.

Conclusions

Using a network MR framework, we provided evidence supporting a positive causal relationship between omega-6 and CHD, which might be partially mediated by TC, LDL-C, and TG.

Keywords

Mendelian randomization
Omega-6
Coronary heart disease
Genome wide association study
Total cholesterol
Low-density lipoprotein cholesterol

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Authors contributed equally to the study: Li-zhen Liao and Wei-dong Li.