DNA Damage and DNA Repair

DNA in human cells is continuously subject to damage. It is in most cases appropriately repaired, leaving relatively few permanent changes. The various kinds of damage comprise chemical modification or loss of DNA bases, single strand or double strand breaks as well as intra- and interstrand crosslinks. Each type of damage can lead to mutations. An important source of mutations are DNA replication and recombination. DNA replication is a particular critical phase, during which misincorporation of nucleotides, DNA polymerase slippage or stalling of replication forks may occur. A further source of mutations are physiological recombination processes that go astray, e.g. in germ cells or lymphocytes.