In addition to encoding the blue prints of an entire organism, it regularly polices itself, detecting errors that occur in its building-block sequence as it replicates. It then remedies the situation by jettisoning the marred region and replacing it with the correct sequence of genetic material. A contingent of enzymes carries out this vital process of DNA repair.
Cancer is one consequence of mutations caused by faulty DNA repair systems.
Their work focuses on a specific type of damage, that caused by ultraviolet radiation. Ultraviolet radiation damages DNA in a very specific way, forming an extra chemical bond between adjacent thymines. This biochemical bump is enough to disturb replication enzymes so that they insert a mismatched base the next time the cell doubles its DNA in preparation for dividing. UV-induced thymine dimers are linked to skin cancer because it is the skin that receives the brunt of solar radiation. To cause cancer, the dimers must form in a so-called tumor suppressor gene, usually the p53 gene.