Figure 1
From: Blood triglyceride levels are associated with DNA methylation at the serine metabolism gene PHGDH
Possible relationships between a SNP, a CpG site and triglyceride levels. The SNP is assumed to act on the methylation levels at the CpG site: (a) The SNP can cause variation independently in the level of methylation and triglycerides (common cause); (b) The CpG site can be on the pathway between the SNP and triglyceride levels. In this case, the SNP is expected to be associated with triglyceride levels; (c) The methylation change can be the consequence of the triglyceride levels variation (reverse causation). Reverse causation can be inferred with a genetic variant (SNPtg) associated with triglyceride levels.
