What distinguishes HNPCC from other colorectal cancer syndromes?

The defining characteristic of Hereditary Non-Polyposis Colorectal Cancer (HNPCC), also known as Lynch syndrome, is the absence of a significant number of colorectal polyps, which distinguishes it from other colorectal cancer syndromes like Familial Adenomatous Polyposis (FAP) that is characterized by hundreds to thousands of polyps. In HNPCC, individuals have a much lower number of polyps, typically a few, and are at risk for colorectal cancer primarily due to inherited mutations affecting DNA mismatch repair genes. This genetic predisposition leads to an increased risk of developing colorectal cancer and other malignancies at an earlier age, but without the polyposis that is seen in other syndromes.

The focus on the absence of polyps is crucial in understanding HNPCC, as it allows for differentiation from conditions that involve significant polyp formation. This clarity can lead to different management and surveillance strategies for affected individuals.