What is a somatic mutation?


A somatic mutation is a change in a gene that occurs during a person’s lifetime in a specific group of cells. These mutations are not present at birth and are not passed down from parents. Instead, they develop in cells as they grow and divide. Somatic mutations are common in many types of cancer because they can cause cells to grow in an uncontrolled way.

Where are somatic mutations commonly found?

Somatic mutations can occur in any tissue in the body. They are typically found in tumor samples or in blood or bone marrow cells when doctors are looking for conditions such as leukemia, lymphoma, or myeloproliferative neoplasms. Genetic tests such as next-generation sequencing (NGS) are often used to detect these mutations.

What does somatic mutation mean?

A somatic mutation affects only the cells in which it appears. As those cells divide, the mutation is copied into the new cells. Because the mutation is not present in every cell of the body, it does not appear in reproductive cells such as sperm or eggs. For this reason, somatic mutations cannot be passed on to children.

Somatic mutations may help explain why a tumor behaves in a certain way or why blood cells grow abnormally. Some somatic mutations provide clues about how long the abnormal cells have been present or whether the disease is likely to respond to specific treatments.

Why is a somatic mutation important?

Finding a somatic mutation can help confirm a diagnosis and guide treatment. In many cancers, specific somatic mutations predict how the tumor may behave or which therapies may be most effective. For example, some targeted treatments work only if a tumor carries a particular mutation. Somatic mutations can also help doctors monitor how a disease changes over time.

Questions to ask your doctor

  • Was a somatic mutation found in my test results?
  • Which gene is affected, and what does that mutation mean?
  • Does this mutation help confirm my diagnosis?
  • Will this mutation affect my treatment options?
  • Will this mutation be monitored over time?
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