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Hereditary Cancer and Genetic Testing

Inherited and acquired mutations

Most genes come in pairs. People inherit one copy of each gene from their mother and one copy from their father. Sometimes, a parent may pass a gene with damage called a "mutation" to their children. The children can pass the same mutation to each of their children. If you were born with a gene mutation that came from your mother or father, you have an "inherited gene mutation." You can view our video on how mutations cause cancer and read more on our page How Are Mutations Inherited?

An inherited gene mutation does not always cause cancer. If you inherit a damaged gene from your father, you still have a normal copy of the same gene from your mother. 

Cell damage can also be acquired. "Acquired" mutations are damage in genes that happen after a person is born. They are caused by “wear and tear” on genes over time. Aging, exposure to hormones, environmental toxins and certain viruses can cause gene mutations. Damage that builds up in cells can lead to cancer.

People with inherited mutations are born with one already damaged gene in all of the cells in their body. This means fewer steps are needed for their cells to develop cancer. 

DNA damage repair

Cells have tools to repair damage. If it cannot be repaired, the body has ways to remove the damaged cell so that it cannot divide and create more damaged cells. This system isn't always perfect, and damage and gene mutations can build up in cells. Over time, this can lead to cancer. 

  • Cancers in people who do not have an inherited mutation are called "sporadic" cancers.
  • Cancers in people who do have an inherited mutation are called "hereditary" cancers. 

image of normal cells becoming cancer cellsimage of cell with inherited mutation becoming a cancer cell

DNA damage repair genes

Certain genes are important for repairing damage. These genes are sometimes referred to as " damage repair" or "DDR" genes. 

  • In normal cells, mutations in damage repair genes increase the chance that the cell will become cancer. This is why inherited mutations in genes that repair damage increase the risk for cancer.
  • In cells that are already cancerous, mutations in damage repair genes can keep the cells from repairing damage caused by treatment. This means that cancer cells with mutations in these genes may be more sensitive to certain treatments.
Last updated January 31, 2022

Key Facts about Hereditary Cancer
Key Facts about Hereditary Cancer

  • Both men and women can carry an inherited mutation. Mothers or fathers can pass an inherited mutation to their sons and daughters.
  • People are born with inherited mutations. Over their lifetime they may develop additional mutations.
  • Most cancers are not caused by an inherited mutation, but are due to mutations that occur over time as a result of aging, environmental exposures, certain viruses, or normal “wear and tear” on cells.
  • About 1 out of 10 cancers will be caused by an inherited mutation.