DNA sequencing: bench to bedside and beyond

Abstract

Fifteen years elapsed between the discovery of the double helix (1953) and the first DNA sequencing (1968). Modern DNA sequencing began in 1977, with development of the chemical method of Maxam and Gilbert and the dideoxy method of Sanger, Nicklen and Coulson, and with the first complete DNA sequence (phage X174), which demonstrated that sequence could give profound insights into genetic organization. Incremental improvements allowed sequencing of molecules >200 kb (human cytomegalovirus) leading to an avalanche of data that demanded computational analysis and spawned the field of bioinformatics. The US Human Genome Project spurred sequencing activity. By 1992 the first 'sequencing factory' was established, and others soon followed. The first complete cellular genome sequences, from bacteria, appeared in 1995 and other eubacterial, archaebacterial and eukaryotic genomes were soon sequenced. Competition between the public Human Genome Project and Celera Genomics produced working drafts of the human genome sequence, published in 2001, but refinement and analysis of the human genome sequence will continue for the foreseeable future. New 'massively parallel' sequencing methods are greatly increasing sequencing capacity, but further innovations are needed to achieve the 'thousand dollar genome' that many feel is prerequisite to personalized genomic medicine. These advances will also allow new approaches to a variety of problems in biology, evolution and the environment.

Figure 1.

Growth of the nucleotide sequence database. The number of published nucleotide sequences, and the total number of base pairs of sequence are plotted versus the date of deposition or publication. Data since 1981 are re-plotted from http://www.ncbi.nlm.nih.gov/Genbank/genbankstats.html and data for sequences published before 1981 are from Dayhoff, Nucleic Acid Sequence Database, Vol. 1 (38). The dates of landmark sequences and technological advances are indicated.