The existence of different versions of the same genetic material in different people is more than a curiosity of interest only to the human geneticist. Polymorphisms are principally of value for their use as genetic "markers" to distinguish different inherited forms of a gene in family studies. Genetic markers are of enormous practical use in medical genetics for:
1. Mapping genes to individual chromosomes by linkage analysis.
2. Presymptomatic and prenatal diagnosis of genetic disease.
3. Detection of heterozygous carriers of genetic disease.
4. Evaluation of high and low-risk persons with a predisposition to common adult disorders, such as coronary heart disease, cancer, and diabetes.
5. Paternity testing and forensic applications.
6. Matching of donor-recipient pairs for tissue and organ transplantation.