Definition of Marker Marker: A piece of DNA that lies on a
chromosome so close to a gene that the marker and the gene are
inherited together. A marker is thus an identifiable heritable
spot on a chromosome. A marker can be an expressed region of DNA
(a gene) or a segment of DNA with no known coding function. All
that matters is that the marker can be detected and trailed. The
term "marker" may be used in other contexts such with a blood
marker or a tumor marker. Last Editorial Review: 4/27/2011
5:27:15 PM Back to MedTerms online medical dictionary A-Z List
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