Detection of hMSH2 and hMLH1 mutations in Chinese hereditary non-polyposis colorectal cancer kindreds

Aim: To establish and validate the mutation testing for identification and characterization of hereditary non-polyposis colorectal Cancer (HNPCC) in suspected Chinese patients.

Methods: Five independent Chinese kindreds with HNPCC fulfilling the classical Amsterdam criteria were collected. Genomic DNA was extracted after informed consent was obtained. The coding region of hMSH2 and hMLH1 genes was detected by polymerase chain reaction (PCR) and denaturing high-performance liquid chromatography (DHPLC). Mutations identified in the proband by DHPLC were directly sequenced using a 377 DNA sequencer, analyzed with a basic local alignment tool (BLAST), and tested in the corresponding family members by direct DNA sequencing.

Results: Mutations were identified in two Chinese HNPCC kindreds. One was the missense mutation of hMSH2 c.1808A-->G resulting in Asp 603 Gly identified in the proband of the fifth HNPCC (HNPCC5) kindred. In the HNP5 kindred, three family members were found to have this mutation and two of them had colorectal Cancer. The other mutation of hMLH1 c.1882A-->G was identified in the HNP2 kindred's proband, which might be the nonsense mutation analyzed by BLAST.

Conclusion: Pedigree investigation and mutation testing of hMSH2 and hMLH1 are the practical methods to identify high-risk HNPCC patients in China.