Wednesday, 12 September, 2007


The scientist who lead the private effort to sequence the human genome has revealed his own complete genetic make-up. The race to decode the human genome may not be entirely over: the loser has come up with a new approach that may let him prevail in the end. In 2003, a US government-financed consortium of academic centers announced it had completed the human genome, fending off a determined challenge from the biologist J. Craig Venter. The consortium’s genome comprised just half the DNA contained in a normal cell, and the DNA used in the project came from a group of people from different racial and ethnic backgrounds. But the loser in the race, Dr. Venter, could still have the last word. In a paper published recently, his research team is announcing that it has decoded a new version of the human genome that some experts believe may be better than the consortium’s. Called a full, or diploid genome, it consists of the DNA in both sets of chromosomes, one from each parent, and it is the normal genome possessed by almost all the body’s cells. And the genome the team has decoded belongs to just one person: Dr. Venter.
Dr. Venter’s race with the consortium began in 1998 when he spotted a quicker method of decoding the human genome. He tried to wrest this rich scientific prize from his academic rivals by co-founding a genome-decoding company called Celera. By June 2000, the two sides were neck and neck preparing a draft sequence of the genome. But in January 2002, Dr. Venter was abruptly fired as president of Celera. The consortium went on to claim victory when it announced its completion of the genome the next year. But the consortium’s genome, though immensely useful to biologists, was full of gaps and only complete in the sense that it was the best that could be done with existing technology. Dr. Venter has spent the last five years and an extra $10 million of his institute’s money in improving the draft genome he prepared at Celera. That genome was based mostly on his own DNA, and the new diploid version is entirely so. His critics may accuse him of an egocentricity of considerable dimension, but by analyzing his own genome he has sidestepped the problems of privacy and consent that could have arisen with other people’s DNA when he made the whole sequence publicly available, as he is doing now.
Like James Watson, the co-discoverer of DNA, whose genome is also being decoded, Dr. Venter believes strongly in making individual DNA sequences public to advance knowledge and hasten the era of personalized genomic medicine.
The unveiling of J. Craig Venter's genome in the open access journal PloS Biology marks the first time that the complete DNA sequence of an individual has been published. In 2001, Venter's company Celera published a version of the human genome that was based on information from himself and four other individuals. At the same time, the publicly-funded Human Genome Project consortium released a consensus human genome, based on DNA samples from over 100 people.
The latest study shows that the amount of genetic variation between individuals is 5-7 times greater than previously suspected. In addition to the expected 3.2 million single DNA 'letter' changes known as SNPs, Venter's genome has nearly a million other variations, which involve small sections of missing, duplicated or 'flipped around' DNA. 'This is the first time that anyone has had an accurate representation of how much variation there is in a human genome', said co-author Stephen W. Scherer of Toronto University.
Commenting on the findings, Venter said that: 'each time we peer deeper into the human genome we uncover more valuable insight into our intricate biology', adding that 'only with additional sequencing of more individual
genomes will we garner a full understanding of how our genes influence our lives'. He also revealed that the results show he has a moderate risk of developing Alzheimer's disease, saying 'there are two groups of people out there, the half that really want to know about themselves and the half that's afraid to know because of all this genetic deterministic nonsense', adding 'knowing what is there will do nothing to change what is already going on in my body'.
The new genome sequence, dubbed HuRef, was pieced together using the 'whole genome shotgun' method previously used by Celera. However, several organisations are now working on faster, cheaper methods that will eventually enable the genome of many more people to be sequenced. DNA pioneer James Watson is the only other person currently having his genome decoded.

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