What syndrome is characterized by autosomal dominant inheritance and a primary feature of right-sided colon cancers without polyposis?

The correct response highlights Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC). This condition is characterized by an autosomal dominant inheritance pattern and is primarily associated with an increased risk of developing right-sided colon cancers. Patients with Lynch syndrome typically do not exhibit the extensive colonic polyps seen in other hereditary syndromes, which distinguishes it from conditions like familial adenomatous polyposis (FAP) and Gardner syndrome.

Lynch syndrome arises from mutations in mismatch repair genes, leading to microsatellite instability and increased susceptibility to several types of cancer, including colorectal cancer, endometrial cancer, and others. The right-sided predominance of colorectal cancers in this syndrome is an important clinical feature that assists in its identification and the genetic counseling of affected families.

In contrast, the other syndromes mentioned involve different inheritance patterns or other primary features. Familial adenomatous polyposis is characterized by thousands of colonic polyps and requires prophylactic colectomy due to the near certainty of cancer development. Gardner syndrome, a variant of FAP, includes extraintestinal manifestations such as osteomas and soft tissue tumors. Peutz-Jeghers syndrome is associated with gastrointestinal hamartomas and a risk of various malignancies, but