- Alterations in DNA that occur after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children. These alterations can (but do not always) cause cancer or other diseases.
Definition from: Physician Data Query via Unified Medical Language System at the National Library of Medicine
- A change in the genetic structure that is neither inherited nor passed to offspring.
Definition from: Human Genome Project Information
at the U.S. Department of Energy
Related discussion in the Handbook
See also Understanding Medical Terminology.