- 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 monitored.
* * *1. A device used to make a mark or to indicate measurement. 2. A characteristic or factor by which a cell or molecule can be recognized or identified. 3. A locus containing two or more alleles that, being harmless, are common and therefore yield high frequencies of heterozygotes which facilitate linkage analysis.- cell m. an identifying characteristic of a cell; e.g., formation of rosettes with sheep erythrocytes as a m. of T lymphocytes, or the presence of surface immunoglobulin as a m. of B lymphocytes.- cell surface m. a surface protein, glycoprotein, or group of proteins that distinguish a cell or subset of cells from another defined subset of cells.- linkage m. a locus at which there is a high probability of heterozygotes (indispensible state for linkage analysis), but in itself perhaps of no clinical interest. SEE ALSO: m. locus.- oncofetal m. a tumor m. produced by tumor tissue and by fetal tissue of the same type as the tumor, but not by normal adult tissue from which the tumor arises.- polymorphic genetic m. inherited characteristic that occurs within a given population as two or more traits.- time m. an instrument that marks the time, usually in seconds or fractions of seconds, on a kymograph record in physiologic experiments.- tumor m. a substance, released into the circulation by tumor tissue, whose detection in the serum indicates the presence of tumor.
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mark·er 'mär-kər n something that serves to identify, predict, or characterize <a surface \marker on a cell that acts as an antigen>: asa) biomarker* * *
mark·er (mahrkґər) something that identifies or that is used to identify; cf. determinant.
Medical dictionary. 2011.
