ABSTRACT
Objective To establish the blood Septin9 methylation detection system for early screening of colorectal cancer based on fluorescence PCR technology .Methods The PCR primer of Septin9 was designed by searching the CpG island site of Septin9 methylation in the NCBI database .The high methylation site of Septin9 gene promoter region was confirmed by PCR amplification and sequencing after extracting DNA from colorectal cancer and para-carcinoma tissues .The fluorescence PCR and TaqMan probe detection technique was designed by aiming at high methylation site for constructing the plasma sample methylation detection sys-tem .Then its accuracy ,specificity ,repeatability and minimum detectable amount were performed the assess-ment and analysis .The SETP9 methylation detection was performed in plasma samples from 57 cases of color-ectal cancer and 30 healthy persons .Results The high methylation site of Septin9 gene in tissue samples was confirmed by sequencing .This site served as the target for designing fluorescence PCR detection system .After assessment ,the accuracy ,specificity and repeatability of this detection system were 100％ ,the lowest detection amount reached 0 .1 ng/μL .Among the plasma samples in 57 cases of colorectal cancer ,the positive rate of Septin9 methylation site detection was 71 .92％ (41/57) and the positive rate of in the patients with pathologi-cal stage Ⅰ and Ⅱ of colorectal cancer reached 64 .2％ .But Septin9 gene had no methylation in plasma of healthy population .Conclusion The plasma fluorescence PCR detection system with Septin9 gene methylation as the target has the characteristics of high sensitivity ,high specificity and high accuracy ,which is the reliable detection technique for the early screening of colorectal cancer and has good clinical application prospect .