Immunogenetics

Immunogenetics or immungenetics is the branch of medical research that explores the relationship between the immune system and genetics.

Autoimmune diseases, such as type 1 diabetes, are complex genetic traits which result from defects in the immune system. Identification of genes defining the immune defects may identify new target genes for therapeutic approaches. Alternatively, genetic variations can also help to define the immunological pathway leading to disease.

Origin
Its origin is usually attributed to Edward Jenner, who discovered in 1796 that cowpox, or vaccinia, induced protection against human smallpox. It took two centuries before the World Health Organization announced in 1979 that smallpox had been eradicated.

The term immunogenetics is based on the two words immunology and genetics, and is defined as “a sub-category of genetics focussing on the genetic basis of the immune reaction” according to MeSH. Genetics (based on Greek γενεά geneá "descent" and γένεσις génesis "origin") is the science researching the transfer of characteristics from one generation to the next. The genes of an organism (strands of DNA) and the transfer of genes from the parent to the child generation of an organism in the scope of possible variations are the basis of genetics.

Immunology deals with the biological and biochemical bases for the body defending germs such as bacteria, virus and mycosis (fungal infections) as well as foreign agents such as biological toxins and environmental pollutants, and failures and malfunctions of these defence mechanisms. Apart from these external effects on the organism, there are also defence reactions regarding the body’s own cells, e.g. in the scope of the bodily reactions on cancer and the lacking reaction of a body on healthy cells in the scope of an immune-mediated disease. Hence, immunology is a sub-category of biology.

The term immungenetics comprises all processes of an organism, which are on the one hand controlled and influenced by the genes of the organism, and are one the other hand significant with regard to the immunological defence reactions of the organism.

History
The medical history of immunology and the immune system dates back to the 19th century. However, the prevention and early defence of diseases was an essential task for all shamans, medicine men and early “doctors” during the entire human evolution. The first Nobel Prize in the field of immungenetics was awarded to Baruj Benacerraf, Jean Dausset and George Davis Snell in 1980 for discovering genetically determined cellular surface structures, which control immunological reactions.

Current research fields
In the last 20 years, research activities focussed on a large number of different questions in immungenetics. Both the acceleration of and the decreasing costs for the sequencing of the genes have resulted in a more intensive research of both academic and commercial working groups. Current research topics particularly deal with forecasts on the course of diseases and therapy recommendations due to genetic dispositions and how these dispositions can be affected by agents (gene therapy).

A special focus is often laid on the forecast regarding and therapy of genetically based autoimmune diseases, which include all diseases caused by an extreme reaction of the immune system against the body’s own tissue. By mistake, the immune system recognises the body’s own tissue as a foreign object which is to be fought. This can result in serious inflammatory reactions which may permanently damage the respective organs. Autoimmune diseases, the outbreak and/or course of which can be visible in the individual genome of the organism, include multiple sclerosis, diabetes type I, rheumatoid arthritis and Crohn’s disease (an example for an immune-mediated disease without genetic disposition is HIV, which is caused by virus). As for multiple sclerosis, an article in the journal Nature dated May 2010 (Baranzini et al.: Genome, epigenome and RNA sequences of monozygotic twins discordant for multiple sclerosis. Nature 2010, 464; S. 1351-1356 – for link see below) showed that this autoimmune disease is not caused by a genetic variation but the course and the treatability are considerably influenced by genetic dispositions. This research was based on analysing three monovular pairs of twins, of which one twin has contracted multiple sclerosis whereas the other one has not.