The purpose of this study is to understand the role bacteria that normally live in the colon may play in colorectal cancer risk, in addition to the hereditary risk to colorectal cancer. The investigators will collect stool specimens as well as additional colon biopsy specimens during the patient's scheduled colonoscopy procedure. The investigators will also collect a questionnaire about diet and lifestyle. The samples will be used to study the impact of diet on naturally-occurring oral and gut bacteria and their influences on human health including risk of cancer.

Inclusion Criteria:

• Male or Female age 18 or older

• Hereditary colorectal cancer syndrome with one of the following:

  • Lynch syndrome, as defined by the presence of a deleterious germline mutation in the MLH1, MSH2, MSH6, PMS2 or EPCAM genes
  • Other hereditary colonic polyposis syndromes, as defined by the presence of a deleterious germline mutation in any one of the following polyposis genes (APC, biallelic MYH, STK11, SMAD4, BMPR1A, or other CRC-risk associated genes at discretion of PI)

Exclusion Criteria:

• Unable to provide informed consent for testing
• Unable to complete English language questionnaire
• Receiving active chemotherapy
• Having completed active chemotherapy less then 12 months prior to day of scheduled lower endoscopy
• No infectious or drug induced colitis less then 12 months prior to day of scheduled lower endoscopy
• No history of inflammatory colitis (Crohn's disease or ulcerative colitis)

Potential research subjects will be identified prospectively within the clinics of the Clinical Genetics and Gastroenterology Services, of MSKCC.