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(mapʹing) 1. The location of genes on a chromosome. 2. The locating of organs or tissues in health or in disease. 3. Determining the anatomic or functional origins or extent of a lesion. SEE: map.

body surface m. Surface m.

body surface potential mapping Surface m.

brain m. Cortical m.

cardiac m. The measurement of the electrical potentials generated by regions of the heart, often to identify a treatable source of an arrhythmia.

cortical m. Establishing the relationship between various structures of the brain and their functions. It is a technique used in neurosurgery to determine which parts of a diseased brain may be safely excised. Maps made of eloquent brain structures help surgeons minimize the damage they do when they remove tumors or seizure foci. SYN: brain m.

epicardial m. Determining the source of an arrhythmia by placing electrodes inside the pericardium (but on the outer surface of the heart).

functional m. 1. Determining those brain structures that are responsible for cognitive, intellectual, speech, sensory, or motor functions. SEE: cortical m. 2. Locating the specific parts of a gene, or of its enhancers or silencers, that influence how the gene is expressed.

gene m. Determining the location of hereditary information carried on chromosomes. In humans, this requires determining the base pairs (chemical code) of each of the estimated 20,000 to 25,000 genes. Once a gene is mapped, that information may be used to compare abnormal genes with normal ones. Molecular biological techniques may then be used to search for methods of treating and preventing conditions resulting from genetic abnormality. SYN: genome m.; linkage map. SEE: gene splicing.

genome m. Gene m.

linkage m. Determination of how close two genes on the same chromosome are to each other. The further apart the two genes are, the more likely there is to be crossing over during meiosis.

lymphatic m. In the staging of cancers, injection of a tracer material near a tumor to determine the regional lymph nodes into which metastatic disease may first spread. SEE: sentinel node (1).

peptide m. A means of identifying proteins electrophoretically after partially hydrolyzing them. Each protein leaves a characteristic pattern of light and dark peptide bands on the electrophoretic paper or gel.

retinal m. Studying the vascular structures and thickness of the retina in order to diagnose its diseases, or study its response to medical or surgical therapies.

surface m. The use of electrodes or other sensors placed on the skin to determine the activities or functioning of dynamic organs inside the body. SYN: body surface mapping; body surface potential mapping.


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