Hereditary Colorectal Cancer

Hereditary colorectal cancer is a category of large bowel cancer (colon or rectum) caused by a genetic susceptibility to certain types of cancer. Individuals with hereditary colorectal cancer have an alteration (known as a mutation ) in their genes which causes them to have an increased risk of developing cancer. These mutations can be passed from generation to generation and are present from birth. If an individual or their family member is identified as having an altered gene (mutation) then this knowledge can be used to encourage proper screening and prevention strategies.

There are currently several syndromes known to be associated with hereditary colorectal cancer. These include: Hereditary Non-Polyposis Colorectal cancer (HNPCC), Familial Adenomatous Polyposis (FAP), Attenuated Familial Adenomatous Polyposis (AFAP), MYH Associated Polyposis (MAP) and Juvenile Polyposis Syndrome (JPS). These syndromes have differing characteristics and are caused by mutations in specific genes.

Chromosomes and genes

There are 46 chromosomes arranged in 23 pairs in each cell of the body and there are approximately 30,000 genes on these chromosomes. Genes are units of hereditary material and contain the body's blueprint or instructions. Each gene produces a protein which has a specific role in the body. Genes come in pairs and each gene has a long code which can be thought of as a long sentence with thousands of letters. Changes in this code can interfere with the normal functioning of the gene and are called mutations. Mutations in specific genes can be associated with certain types of cancer. Mutations can be transmitted from generation to generation in the sperm or egg of the parent.