Under a linkage analysis (engl .: linkage analysis) is understood in genetics a mapping method for genes . In doing so, one examines as many genetic features of a chromosome as possible to determine how often they have separated during recombination events.
According to Mendel's third rule, there is a 50% probability that genes on different chromosomes will separate . However, if two genes separate less often on a chromosome, one speaks of gene coupling . The closer the genes are to each other, the less likely it is to separate in a recombination event.
Using many cross-breeding experiments over several generations, one can determine the probability of separation. This indicates the relative distance between genes, which is measured in centiMorgan (cM). 1 cM is the distance between two genes that were decoupled in only one percent of all recombinations examined. Since visually conspicuous features (markers) are not very common, molecular markers such as B. RFLPs , AFLPs , microsatellites and SNPs .
If cross-breeding experiments are not possible, for example when mapping disease genes in humans, mapping can also be carried out by examining family trees ( family tree analysis ). However, this requires at least three generations and a large number of family trees.
Depending on the data available, this evaluation is carried out using more or less complicated statistical methods.