genetic marker

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A gene, DNA sequence, or gene product whose inheritance can be traced through a pedigree or phylogeny. Genetic markers are used in paternity testing, studies of evolution, and evaluating genetic contributions to phenotypes including disease. Genetic markers associated with certain diseases can often be detected in the blood serum, where their presence is used to determine whether a person is at high risk for developing a disease.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a specific gene that produces a recognizable trait and can be used in family or population studies