Acquired and inherited cancer gene variants

Our bodies are made up of tiny building blocks called cells. Inside nearly every cell is a set of genes. Genes are the instructions for your body to work.

If a gene is changed, it may not give the correct instructions anymore. A change in a gene is called a genetic variant or gene mutation.

Over time, genetic variants in a cell may stop the cell working normally. Cancer may develop if cells like this multiply in an abnormal way and grow out of control.

A gene change that is passed from parent to child is called an inherited variant or mutation. This type of gene change is there from birth. It is in almost every cell in the person’s body for their whole life.

Some inherited gene variants cause a higher risk of certain types of cancer. The gene variant by itself does not cause cancer. But it may allow other damage to build up faster in cells. This increases the chance that cancer will develop.

Cancer gene variants cannot skip or miss a generation. If one of your parents has a gene variant, there is a 1 in 2 (50%) chance it has passed to you. You either inherit it or you do not. If you do not inherit the variant, you cannot pass it to your children.

Sometimes it can seem like the cancer skipped a generation. This is usually because a person in the family has the variant which is then passed on to their child. But the person does not develop cancer themselves.

This might happen because of the following reasons:

• Having a cancer gene variant raises a person’s risk of developing cancer. But it does not mean they will definitely develop cancer. Sometimes the person does not develop cancer, but their child inherits the variant and does. This can seem like the cancer gene has skipped a generation.
• A person may inherit and pass on a cancer gene variant for a cancer type they cannot develop themselves. For example, gene variants linked to breast and ovarian cancers can pass through the father’s side of the family. A father who inherits this type of variant is unlikely to develop breast cancer and cannot develop ovarian cancer. But they still have a 1 in 2 (50%) chance of passing the variant to their children. If their daughter inherits the variant and develops breast or ovarian cancer, it can seem like the cancer gene has skipped a generation.

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