Familial colon cancer is a cluster of colon cancer within a family. Most cases of colon cancer occur sporadically in people with little to no family history of the condition. Approximately 3-5% of colon cancer is considered "hereditary" and is thought to be caused by an inherited predisposition to colon cancer that is passed down through a family in an autosomal dominant or autosomal recessive manner. In some of these families, the underlying genetic cause is not known; however, many of these cases are caused by changes in the APC, MYH, MLH1, MSH2, MSH6, PMS2, EPCAM, PTEN, STK11, SMAD4, BMPR1A, NTHL1, POLE, and POLD1 genes (which are associated with hereditary cancer syndromes). An additional 10-30% of people diagnosed with colon cancer have a significant family history of the condition but have no identifiable genetic change in a gene known to cause a hereditary predisposition to colon cancer. These clusters of colon cancer are likely due to a combination of gene(s) and other shared factors such as environment and lifestyle.