variable expressivity

Definition of variable expression

variable expression

(VAYR-ee-uh-bul ek-SPREH-shun)
Refers to the difference in the way that signs and symptoms of a genetic condition can show up in individual patients who have that condition. For example, some patients with neurofibromatosis type 1 may have only mild symptoms, such as brown spots and freckling on the skin, and others may have more severe symptoms, such as brain tumors and tumors on the nerves.

Source: NCI Dictionary of Cancer Terms