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DNA Genetics in Colon Cancer: Genetics and Colon Cancer Risk

written by: DulceCorazon•edited by: Emma Lloyd•updated: 7/27/2010

Genetic predisposition increases a person's risk to develop colon cancer. Find out more about the DNA genetics in colon cancer.

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    Studies have shown that the third most frequently occurring cancer in both sexes is colon cancer. Colon cancer is an abnormal, disorderly, and uncontrollable growth of cells in the large intestine, where the body’s waste material is stored. Abnormal mushroom growths usually start in the inner surface of the colon or rectum and some eventually become malignant tumors, while others remain as benign polyps. Once a polyp develops into a tumor, it grows very fast and it can immediately block, invade, break through the colon walls then spread through other parts of the body. Colon cancer commonly presents with rectal bleeding, marked decrease in the diameter of stools, constipation or diarrhea, unexplained weight loss and abdominal pain. It may also manifests with anemia and total prevention of excretion.

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    Colorectal Cancer Risk Factors

    There are major risk factors that predispose a person to develop colon cancer. These are age, polyps in the colon, diet and lifestyle, chronic inflammatory bowel disease, and familial or genetic history. Among these, research showed that 30% of cases are associated to genetic factors where either one or both parents possess the defective gene and pass it on to the child. The majority of cases are sporadic in nature, occurring in people with no known history of colon cancer in the family.

    Learn about the DNA genetics in colon cancer as evidenced in familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, juvenile polyposis and Peutz-Jeghers syndrome .

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    Familial Adenomatous Polyposis (FAP)

    Familial adenomatous polyposis is an inherited disease in which thousands of polyps form in the large intestine of the body. A change in MUTYH and APC gene causes this disease. Because polyps may become malignant, having several polyps increase the chances for colorectal cancer.

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    Herditary Nonpolyposis Colorectal Cancer (HNPCC)

    Hereditary nonpolyposis colorectal cancer is responsible for up to seven percent of colorectal diseases. Mutations or changes in MLH1, MSH2, MSH6, and PMS2 genes are accountable for this condition.

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    Juvenile Polyposis (JP)

    Juvenile Polyposis is a condition where polyps develop in the colon of young adults below the age of twenty. When these polyps are not removed by the age of thirty five, there is twenty percent chance that they will develop into colon cancer. The genes responsible for JP are SMAD4 and BMPR1A.

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    Peutz-Jeghers Syndrome (PJS)

    PJS is a disease characterized by the development of growths or polyps in the stomach and intestines. These polyps increase the risk for developing colorectal cancer. The mutation in STK11 causes this condition.

    These are the different DNA genetics in colon cancer which are responsible for developing certain diseases that when gone unmanaged may develop into colorectal cancer. Having these mutated genes does not necessarily dictate that a person will have colorectal cancer but rather increases one’s risk for it.

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    References

    National Cancer Institute: Genetics of Colorectal Cancer

    deCODEme: Colorectal Cancer