Personal genetic maps on the horizon

The potential for personal genetic maps has come three steps closer to reality with the publication of results from three studies using powerful next-generation genome sequencing technology. The studies are published in this week’s edition of Nature.

By efficiently mapping two genomes of different ethnic origin, and a cancer genome, the three large international research teams have demonstrated the potential of new rapid genetic sequencing techniques to quickly and economically map a personal genome.

All three papers demonstrate the utility of the Illumina (formerly Solexa) massive parallel sequencing technique that enables very high throughput: one hundred million DNA fragments can be sequenced in parallel on a chip.

This approach is already being used widely in fields ranging from medical re-sequencing through to assessment of copy number variation. It is effective for accurate, rapid and economical re-sequencing of whole genomes and supports the potential of personal genome sequencing which, it is speculated, will become a clinical tool in the near future supporting diagnosis, prevention and therapy of human diseases.

Mapping ethnic differences

By sequencing the genomes of both an Asian and an African individual, two research teams shed light on how the human genome varies with ethnicity.

In the first paper, a large international collaboration led by David Bentley of Illumina Cambridge Ltd in the United Kingdom, describes using the massive parallel sequencing approach to sequence and initially characterize the genome of an African individual from the Yoruba ethnic group of West Africa.

In the second paper, an international collaboration led by Jun Wang of the Beijing Genomics Institute at Shenzhen, China, reports using the same technology to sequence the genome of an East Asian individual. Wang and colleagues illustrate the potential of personal genomics in disease diagnosis by comparing this genome with the other individual genomes already available—those of J. D. Watson and J. C. Venter.

Getting personal with a cancer genome

Harnessing the power of massive parallel sequencing technology has also enabled an individual cancer genome to be sequenced for the first time, identifying mutated genes that probably have a role in the development of acute myeloid leukemia.

Acute myeloid leukemia is a white blood cell cancer that affects around 13,000 adults yearly in the United States alone: about one-third of those affected will die from the disease.

In the third paper this week, Elaine Mardis from the Washington University School of Medicine in the US and colleagues sequenced cancerous and normal tissue from a patient with acute myeloid leukemia. They identified ten mutated genes by comparing the two sequences. Of these, two were previously reported to be associated with acute myeloid leukemia, whereas the others probably represent new genes important for the development of the disease.

The authors suggest that whole-genome sequencing may be the only effective means for discovering all of the mutations in the disease that are relevant for pathogenesis. Previously used methods failed to reveal clues about the development of this tumor, highlighting the importance and potential of the massive parallel sequencing technique. This high-throughput sequencing method could be applied to other cancers and aid the design of targeted therapeutics.