A candidate gene is a gene suspected to be involved with a particular disease, condition, or abnormality. Researchers find candidate genes through a painstaking process which involves sifting through large amounts of genetic material to identify genes and determine what they do. Once a candidate gene can be positively linked with a specific medical subject of interest, researchers can start to explore the variations in the gene and the way in which it acts on the body.
To find a candidate gene, researchers first identify the area of a particular chromosome which they believe is involved in the process of a genetic condition. Then, they look for specific genes within that area to see if they can find a gene which might be a likely suspect. Researchers may use information about the protein product of a particular gene to find out whether or not it is a candidate gene; protein products are the molecules which are constructed using the information in a gene.
Candidate gene mapping is a lengthy process. Many researchers use algorithms to narrow down possibilities, rather than trying to plow through genetic information manually. Once possibilities are identified, they can be subjected to analysis to determine whether or not they are candidate genes. Given the huge number of genetic conditions, paired with genes which are found in everybody, identifying candidate genes is a bit like looking for a very small needle in an extremely large haystack.
Finding candidate genes is important. From a pure research level, scientists are interested in finding out precisely what is responsible for various genetic conditions, and how defective genes cause people to develop inherited diseases and other abnormalities. Researchers are also interested in the interactions between defective genes, how defective genes develop, and the evolutionary history of such genes. Some harmful genetic conditions are related to adaptations which were originally designed to help people thrive in harsh environments, for example.
From the perspective of patient care, the ability to identify the genes involved in disease processes can be useful in diagnosis, as patients can be tested to determine whether or not they carry the gene responsible for a condition. People can also undergo genetic testing to see if they are at risk of passing on dangerous genetic material to their children. Theoretically, it may be possible to manipulate harmful genes to turn them off or alter their expression so that people with these genes will not experience the medical conditions associated with them.