CTH and hyperhomocysteinemia: Previous studies have found that hypermethylation of the CTH promotor in hyperhomocysteinemia in mice can lead to the decrease of CTH expression, which in turn prevents homocysteine from being catabolized and causes vascular endothelial cells injury, eventually results in CAD (Li et al., 2015; Giannakopoulou et al., 2017).