Gardner Syndrome:


Inherited gene mutations


A small percentage of colorectal cancers result from identified gene mutations. These cancers are autosomal dominant, meaning you need to inherit only one defective gene from either of your parents. If one parent has the mutated gene, you have a 50 percent chance of inheriting the mutation. Although inheriting a defective gene greatly increases your risk, not everyone with a mutated gene develops cancer.
One genetic defect that plays a key role in colorectal cancer occurs in the adenomatous polyposis coli (APC) gene. When the APC gene is normal, it helps control cell growth. But if it's defective, cell growth accelerates, leading to the formation of multiple adenomatous polyps in your intestinal lining. Conditions related to APC gene defects include:
  • Familial adenomatous polyposis (FAP). This is a rare, hereditary disorder that results from an APC gene defect. FAP causes you to develop hundreds, even thousands of polyps in the lining of your colon and often in your upper intestine, beginning in your teenage years. If these go untreated, your risk of developing colon cancer by age 45 is nearly 100 percent. The encouraging news about FAP is that in some cases, genetic testing can help determine whether you're at risk of the disease.
  • Gardner's syndrome. This syndrome is a variant of FAP. This condition causes polyps to develop throughout your colon and upper intestine. You may also develop noncancerous tumors in other parts of your body, including your skin (sebaceous cysts and lipomas), bone (osteomas) and abdomen (desmoids).
  • Hereditary nonpolyposis colorectal cancer. This is the most common form of inherited colon cancer. It too results from a defect in the APC gene, but unlike people with FAP or Gardner's syndrome, people with hereditary nonpolyposis colorectal cancer tend to develop relatively few colon polyps. They do, however, often have tumors in other organs. Hereditary nonpolyposis colorectal cancer includes Lynch I and Lynch II syndromes. People with Lynch I syndrome usually develop a small number of polyps that quickly become malignant. Those with Lynch II syndrome tend to develop tumors in the breast, stomach, small intestine, urinary tract and ovaries as well as in the colon.