In Gardner's syndrome, which gene mutation is primarily involved?

In Gardner's syndrome, the primary gene mutation involved is the APC (Adenomatous Polyposis Coli) gene. This genetic condition, which is a variant of familial adenomatous polyposis (FAP), is characterized by the development of multiple colorectal adenomatous polyps, which carry a high risk for progression to colorectal cancer if not managed appropriately. Additionally, individuals with Gardner's syndrome often present with extraintestinal manifestations such as desmoid tumors, osteomas, and epidermoid cysts, all of which are associated with mutations in the APC gene.

The APC gene acts as a tumor suppressor gene, playing a critical role in the regulation of cell growth and the Wnt signaling pathway. A mutation in this gene predisposes individuals to multiple polyps and subsequent malignancies due to the loss of its tumor-suppressive function. This genetic understanding is essential for both diagnosis and management in patients with Gardner's syndrome.

In contrast, BRCA1 is primarily associated with breast and ovarian cancers, while PTEN is involved in Cowden syndrome, which presents with different clinical features. MLH1 is linked to Lynch syndrome (hereditary nonpolyposis colorectal cancer), which similarly has a different genetic basis and manifestations.