At minimum, I find 20 copy errors when converting a professionally edited 350 - page print book to «e». (readersentertainment.com)
Mutations can be caused by copying errors in the genetic material during cell division and by exposure to radiation, chemicals, or viruses, or can occur deliberately under cellular control during the processes such as meiosis or hypermutation. (sciencedaily.com)
DNA copying errors during the production of sperm and eggs must have led to the gene being repeatedly duplicated. (newscientist.com)