SOPHISTICATED DNA REPAIR SYSTEMS. “Joining two duplexes with double-strand (DS) breaks at their ends is today called ‘non-homologous end joining’ (NHEJ), and cells have various biochemical systems for carrying it out. NHEJ is but one of a series of biochemical systems that have evolved to protect genomes from many kinds of physical and chemical damage. The partial list…gives an idea of how extensive and sophisticated the physiology of DNA damage repair has evolved to be.”
http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2014.271130/full