Attenuated adenomatous polyposis with MSH6 variation: two case reports

Abstract

Background: Adenomatous polyposis (AP) is a genetic disorder characterized by the occurrence of numerous adenomatous polyps in the colon and rectum and can be classified into classical AP (CAP) and attenuated AP (AAP). AAP is diagnosed when the number of observed adenomas is between 10 and 99. The detection of AAP is significantly increasing mainly due to the improvement of the imaging technique and application of the screening program for colorectal cancer detection. Currently, the germline variations of the APC and MUTYH genes are reported as the main cause of CAP. However, the underlying genetic basis of AAP is not well understood. In this study, we report two cases of AAP with MSH6 variations. Case reports: The two patients had multiple colon polyps and were diagnosed with AAP. The two received genetic consultation; and, for follow-up purposes, both patients agreed to be tested for an underlying genetic condition through next generation sequencing (NGS). Germline MSH6 variations were detected in both patients. Conclusion: Minor portion of AAP can cause by genetic mutation in MSH6, and further research is needed.