Researchers have discovered 2,363 new DNA sequences corresponding to 730 regions on the human genome by using new approaches. These sequences represent segments of the genome that were not charted in the reference map of the human genome.
"A large portion of those sequences are either missing, fragmented or misaligned when compared to results from next-generation sequencing genome assemblies on the same samples," said Dr. Evan Eichler, senior author on the findings published April 19 in the advanced online edition of Nature Methods. Eichler is a University of Washington (UW) professor of genome sciences and an investigator with the Howard Hughes Medical Institute. "These findings suggest that new genome assemblies based solely on next-generation sequencing might miss many of these sites."
Dr. Jeffrey M. Kidd was lead author of the article, which described the new techniques the research team used to find some of the missing sequences.
Kidd headed the study while earning his Ph.D. at the University of Washington in the Eichler lab. Kidd is now a postdoctoral fellow at Stanford University.
"Over the past several years, the extent to which the structure of the genome varies among humans has become clearer. This variation suggested that there must be portions of the human genome where DNA sequences had yet to be discovered, annotated and characterized," he said "We hope that these sequences ultimately will be included as part of future releases of the reference human genome sequence."
The reference genome is a yardstick or standard for comparison for studies of human genetics.
The human reference genome was first created in 2001 and is updated every couple of years, Kidd explained. It's a mosaic of DNA sequences derived from several individuals. He went on to say that about 80 percent of the reference genome came from eight people. One of them actually accounts for more than 66 percent of the total.
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University of Washington