There are 2 main inherited syndromes that can lead to colorectal cancer:
Lynch syndrome, also known as HNPCC or hereditary non-polyposis colorectal cancer
Familial adenomatous polyposis (FAP)
But other, less common inherited syndromes are linked with colorectal cancer as well. These include:
Turcot syndrome. People with this rare disorder have a greater risk of polyps that can become cancerous, colon cancer, and brain tumors. Defects or mutations in a few different genes are linked to this syndrome. These include the gene linked to FAP and the genes linked to Lynch syndrome.
PJS (Peutz-Jeghers syndrome). With PJS, a child only needs to inherit one abnormal gene from one parent. People with this rare inherited disorder may have:
Dark blue or brown spots or freckles in or around the mouth including the lips, and around the eyes, nostrils, and anus. Dark spots may also appear on the fingers. These may fade by adulthood.
Many polyps in the GI or gastrointestinal tract. These may be benign at first, but can become cancer over time.
Increased risk of benign or noncancerous tumors of the ovaries and testicles
Increased risk of cancers of the stomach, small intestine, breast, ovaries, colon, lung, cervix, and pancreas
Juvenile polyposis syndrome. This is a rare inherited disease that typically appears before age 20. People with this syndrome have many benign, noncancerous polyps throughout the GI tract. But there is a chance that these polyps can become cancer. Other symptoms can include diarrhea, GI bleeding, and an abnormal loss of protein from the GI tract (protein-losing enteropathy). Often it may seem that a child is the first in his or her family to have this disease. But it’s possible to inherit it from one parent who has the abnormal gene, but no symptoms.
MAP or MYH-associated polyposis. Mutations in the MYH gene raise the risk for multiple colorectal polyps or colorectal cancer. People with MAP may have just a few polyps, or hundreds of polyps. Unlike most colorectal polyp and colorectal cancer disorders, a person with MAP has defects in both copies of their MYH gene. The symptoms of MAP are very similar to both FAP and another form of that disorder called AFAP, or attenuated FAP. Genetic testing for mutations in the MYH gene is available. Testing should be considered if you may have FAP or AFAP, but don’t have a mutation in the gene linked to those disorders. Experts don’t know if people with only one MYH mutation have a higher than average risk for colorectal polyps and cancer.
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