The largest amount of research on gene mapping at present is centered on mapping genes associated with hereditary susceptibility for diseases. Headlines in the popular press such as 'scientist discovers gene for breast cancer' drive the public's curiosity on how their genes influence their health and longevity. As a result, research in this area will continue to be well-funded and will continue to reveal much about how our genetic heritage can influence our individual futures. Gene mapping is a highly statistical endeavor, but the basic principle is simple. The essence of gene mapping is to find which markers on a genetic map are distributed among family members in a way that is similar to how a given trait is distributed.
Markers usually consist of some type of detectable variation in the nucleotide sequence.
Sometimes the physical location of the markers is known, and sometimes researcher use relative distances among markers to narrow down a location. In the first case, a physical distance can be used. In the second case, a recombination distance is determined. It is assumed that the markers whose pattern of inheritance is most similar to the pattern of inheritance exhibited by the trait of interest are in closest proximity to the gene or genes responsible for that trait. The degree of ease with which genes affiliated with particular traits can be mapped is a function of the density of available markers and the pattern of inheritance of the trait of interest.