(KROH-muh-some …) 
One of a pair of chromosomes that is part of the 46 chromosomes found in the nucleus of most human cells. Specific changes in chromosome 17 may be found in patients with certain genetic conditions and some types of cancer, including bladder cancer, brain cancer, and leukemia. Checking for these changes may help diagnose cancer or find out if cancer has come back. Chromosome 17 is a type of tumor marker.