Individual Genetic Variation 5X Greater Than Thought

The First Diploid Sequence of an Individual Human: The highly accurate sequence suggests that our genetic code is five times as variable as we thought

SOURCE: "The Diploid Genome Sequence of an Individual Human" Samuel Levy et al.
PLoS Biology 5: e254

RESULTS: Genomics pioneer Craig Venter and his colleagues have generated a highly accurate sequence of Venter's genome, one that includes the DNA sequences inherited from both his mother and his father.

WHY IT MATTERS: The genome sequence generated by the Human Genome Project, the massive, distributed effort to sequence human DNA that was completed in 2003, was a milestone in the history of biology. But the DNA sequence produced by the project represented just one set of chromosomes (every human has two sets, one inherited from each parent), and it drew on DNA samples from many individuals. As a result, it didn't reflect some of the variability between individuals. ­Venter's diploid genome suggests that genetic variation between individuals is approximately 0.5 percent, not the 0.1 percent that earlier sequencing projects suggested.

METHODS: In the new study, researchers used a method of gene sequencing called Sanger sequencing. The method is more expensive than newer approaches, but it generates longer strings of DNA that are easier to assemble into a complete genome.

NEXT STEPS: Venter and his colleagues plan to add phenotypic information, such as medical records and physical characteristics, to the database housing his genome. This will allow scientists to begin analyzing an individual's genomic information in the context of his or her actual traits.