NCI Dictionary of Genetics Terms
Welcome to the NCI Dictionary of Genetics Terms, which contains technical definitions for more than 150 terms related to genetics. These definitions were developed by the PDQ® Cancer Genetics Editorial Board to support the evidence-based, peer-reviewed PDQ cancer genetics information summaries.
- variable expression
- listen(VAYR-ee-uh-bul ek-SPREH-shun)
- Variation in the manner in which a trait is manifested. When there is variable expressivity, the trait may vary in clinical expression from mild to severe. For example, the condition neurofibromatosis type 1 may be mild, presenting with café-au-lait spots only, or may be severe, presenting with neurofibromas and brain tumors.