A linkage map shows the frequencies of recombination between markers during crossover
A linkage map is a genetic map of a species or experimental population that shows the position of its known genes or genetic markers relative to each other in terms of recombination frequency, rather than a specific physical distance along each chromosome. A linkage map is a genetic map of a species or experimental population that shows the position of its known genes or genetic markers relative to each other in terms of recombination frequency, rather than a specific physical distance along each chromosome. Linkage mapping is critical for identifying the location of genes that cause genetic diseases.
The important thing to realize about linkage is that it helps researchers identify the locations on chromosomes at which specific genes exist. Indeed, linkage is critical for mapping and identifying genes when we are trying to discover which gene is responsible for a specific phenotype. In a genetic screen, mapping allows scientists to link genes to their functions.
A genetic map is a map based on the frequencies of recombination between markers during crossover of homologous chromosomes. The greater the frequency of recombination (segregation) between two genetic markers, the farther apart they are assumed to be. Conversely, the lower the frequency of recombination between the markers, the smaller the physical distance between them. Historically, the markers originally used were detectable phenotypes (enzyme production, eye color) derived from coding DNA sequences; eventually, confirmed or assumed non-coding DNA sequences such as microsatellites or those generating restriction fragment length polymorphisms (RFLPs) have been used. Genetic maps help researchers to locate other markers, such as other genes by testing for genetic linkage of the already known markers.