Germline mutations in patients with multiple colorectal polyps in China

BACKGROUND AND AIM: Multiple colorectal polyps are relevant in hereditary colorectal cancer (CRC) syndromes, which are thought to be caused by multiple events including germline mutations. This study was aimed to characterize germline mutations in Chinese patients with multiple colorectal polyps. METHODS: Patients with > 10 colorectal polyps at the Department of Gastroenterology of the PLA Army General Hospital were enrolled from January 2014 to December 2015. These patients were divided into the high-risk, moderate-risk, and mild-risk groups. White blood cell samples were collected, and DNA was extracted to sequence a panel of 19 genes previously associated with CRC by next-generation sequencing. RESULTS: A total of 96 patients were enrolled in the study. Pathogenic germline mutations were found in 24 (24/33, 72.73%), nine (9/24, 37.5%), and three patients (3/39, 7.7%) in the high-risk, moderate-risk, and mild-risk groups, respectively. Based on the results given, we suggested a strategy about gene sequencing test for the patients with multiple polyps, and the sensitivity and specificity of the screening strategy were 97% and 57%, respectively. Four of eight patients with MUTYH pathogenic germline mutations had the c.A934-2G monoallelic germline mutation, whereas three of eight patients had the C55T MUTYH germline mutation. Concurrent pathogenic germline mutations in APC and MUTYH were also observed. CONCLUSIONS: A genetic screening strategy comprising 19 genes was effective to screen for hereditary CRC syndromes in patients with multiple colorectal polyps. The MUTYH germline mutation hotspots in Chinese patients may be different from those in Caucasian patients.