The effects of high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol (LDL‐C), and triglycerides on the risk of coronary heart disease (CHD) have been investigated by numerous MR studies.21 For HDL‐C, univariable MR suggested a causally protective role against CHD risk, whereas univariable MR‐Egger provided no evidence of a causal effect and the test for directional pleiotropy was statistically significant at the 5% level.8 A null causal effect for HDL‐C was also reported from a multivariable MR analysis that included LDL‐C and triglycerides using the multivariable IVW method,7 although a small but protective causal effect was estimated in a further multivariable MR analysis using a wider range of 185 genetic variants.22
