The recognition of the association between circulating C-reactive protein (CRP) levels and risk of coronary heart disease (CHD) has led to an increased emphasis on CRP genetic effects on CRP level and CHD. However, the causality of CRP variants remains uncertain.The objective of this study is to evaluate the association of CRP gene variants and CRP levels in CHD in Chinese Han population. We conduct case-control study in CRP-Han study participants. The common single-nucleotide polymorphisms (SNPs) in the CRP gene, haplotypes, and plasma CRP levels are detected. A Mendelian randomization analysis will be used to help test the likelihood of causal association of gene-CRP levels, CRP levels-CHD and gene-CHD. The investigators hypothesize that CRP gene variants influence the protein level and may participate in CHD progress.