Cheaper Genome Mapping on the Way

Researchers have used off-the-shelf instruments and chemical reagents to create a DNA sequencing method that may dramatically reduce the cost of genome mapping.

Investigators at Harvard Medical School (Boston, MA, USA) have converted a commonly available, inexpensive epifluorescence microscope into an automatic non-electrophoretic DNA sequencing instrument. The microscope with attached digital camera and associated computers was used to retrieve data that were generated by a cell-free, mate-paired library that provided single DNA molecules that were amplified in parallel to one-micrometer beads by emulsion PCR (polymerase chain reaction). Millions of gene fragments were immobilized in a polyacrylamide gel and subjected to automated cycles of sequencing and four-color imaging. Fluorescing DNA nucleotides were detected by the microscope's camera, and the results were sent to computers that reinterpreted the data as a linear sequence of base pairs.

Today it costs more than U.S.$20 million dollars to map a complete human genome. Using the new method, as described in the August 4, 2005, online edition of Science, the price can be reduced to about $2.2 million. The authors believe that in the near future this cost can be reduced to as little at $1,000, which would bring genome mapping into the realm of clinical diagnostics. Senior author Dr. George Church, professor of genetics at Harvard Medical School, said, "The cost of $1,000 for a human genome should allow prioritization of detailed diagnostics and therapeutics, as is already happening with cancer.”




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