Detection of mutation of the p53 gene with high sensitivity by fluorescence-based PCR-SSCP analysis using low-pH buffer and an automated DNA sequencer in a large number of DNA samples.

Detection of mutations in genes responsible for hereditary diseases or tumors is important clinically. It is necessary to establish a simple technique for screening mutations in large numbers of samples. The polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method has proved to be a useful technique for analyzing mutations or DNA polymorphisms. Non-radioisotopic versions using fluorescent dye and an automated DNA sequencer have also been exploited to extend this technique into the clinical field. We have examined mutations of exons 5-9 of the p53 gene in 112 colorectal, 28 esophageal and 33 hepatocellular carcinomas by fluorescence-based PCR-SSCP (F-SSCP) under various conditions. We found 64 types of mutations in 63, 17 and 12 cases of colon, esophageal and hepatocellular carcinomas by F-SSCP. We determined the sequence of all samples, and confirmed that all mutations were successfully detected by F-SSCP. With the low-pH buffer system, 61 types of mutants were detected, while 51 types were detected by TBE and 57 types were detected by TBE with glycerol gel. The polyacrylamide gel in TME or TBE without glycerol was tough and could be used repeatedly, but the glycerol containing gel was fragile and could not stand repeated use. Thus, use of a low-pH buffer in the electrophoresis of F-SSCP is simpler and better at detecting mutations than the conventional TBE buffer system. We believe that low-pH F-SSCP analysis is an efficient and powerful technique for examination of a large number of samples, in particular clinical specimens obtained by biopsy or surgery.