Medical implications of DNA repair.

When the sun damages the skin, it also impairs the DNA. The DNA repair system is needed to maintain the genetic integrity of the epidermis. Defects in DNA repair (eg, xeroderma pigmentosum) commonly result in skin cancer. Sun-screens are important for preventing sun damage, but inadequate application by consumers is common, and protection against DNA damage is incomplete. The human population varies widely in its formation and response to DNA damage. Sequencing of individuals' DNA repair genes has revealed unexpected diversity, and some polymorphisms may be related to skin cancer risk. DNA damage has been linked to immune suppression in humans, and variations in this immune response also are linked to cancer risk.