The 10 studies comprised a total of 24,552 participants and 4,209 incident MetS cases [4–7, 11, 12, 23–25], of which five studies treated the CRP level as categorical variable, and four studies treated the CRP level as continuous variable with log transformation, and our current study in Chinese treated the CRP as both categorical and continuous variables (Additional file 1: Table 7). This evidence concerns the gene CRP and metabolic syndrome.