DNA sequencing was first carried out in the 1970s. British biochemist Dr. Frederick Sanger developed a method of sequencing DNA that has become the gold standard. This method involves copying single-stranded DNA using chemically altered bases, called dideoxynucleotides, that cause the DNA chain to terminate when these bases are incorporated. The terminated chains are then resolved by capillary electrophoresis.
Initially, Sanger sequencing’s throughput was only tens to hundreds of bases per day, but by the mid-1980s the first commercial DNA sequencers (from Applied Biosystems) based on the Sanger sequencing method were producing thousands of bases of sequence a day. By automating the data collection (up to that time the base sequences had to be input into a computer by hand), the accuracy and throughput of DNA sequencing grew enormously. By the mid-1990s, DNA sequencers could be found in many laboratories and were producing as many as a million bases, or a megabase, of sequence per day.