After information extraction and discussing, 14 studies were further excluded (7 duplications, 4 without sufficient data, 2 on HNPCC and 1 review paper), resulting in 40 eligible studies with 13,896 CRC cases and 18,839 controls reporting the association between the NAT2 acetylator phenotypes and CRC risk for this meta-analysis [9]–[48]. The gene discussed is NAT2; the disease is colorectal carcinoma.