ABSTRACT
The human genome reference sequence, however, is just a single representative snapshot, and an artificial one (different parts of the sequence originated from different people). DNA repair mechanisms seek to minimize the effects of DNA sequence variation, and outlines the different DNA repair mechanisms that work in the people cells. The DNA changes are occasionally induced by radiation and chemicals in our environment, but the great majority arise from endogenous sources: spontaneous errors in normal cellular mechanisms regulating chromosome segregation, recombination, DNA replication, and DNA repair, plus spontaneous chemical damage to DNA. Instead, according to the type of DNA lesion, one of several alternative DNA repair pathways is used. Interstrand cross-links seem to be repaired using a combination of nucleotide-excision repair, translesion synthesis, homologous recombination, and a complex of multiple different protein subunits that are encoded by genes mutated in Fanconi anemia.
