Different covariates including region (Asia vs. non-Asia), sample size (≥100 vs. <100), control type (health control vs. non-CRC disease), sample source (plasma vs. serum), assay methods (RT-PCR vs. other methods in quantitative analysis; MSP vs. other methods in qualitative analysis), and methylation gene (SEPT9 vs. other genes in qualitative studies) were applied in the subgroup analysis (Table 2). The gene discussed is SEPTIN9; the disease is colorectal carcinoma.