Genetic Mediators of Radiation Sensitivity and Radiation Resistance

There are genetic conditions under which humans are more radiosensitive or radioresistant. The genes involved in these differences have been conserved through evolution in bacteria, yeast, multicellular organisms, various vertebrate species, and, ultimately, humans. Some of these conditions of radiosensitivity have led to susceptibility to diseases including cancer, rapid aging, and sensitivity to chemotherapeutic agents, as found in patients with Fanconi Anemia, Bloom’s Syndrome, Nijmegen Break Syndrome, and others. Radiation resistance has been found in animal or plant species that have been exposed to increased levels of continuous irradiation in which the process of natural selection has led to duplication or creation of new radiation resistance genes. Examples in many plant and animal species provide valuable information on mechanisms of response to irradiation that may apply to space irradiation and radiation countermeasures against nuclear reactor accidents or nuclear bomb explosions.