Sept. 4 : Controversial genomics pioneer Craig Venter has sequenced his own genome, and described it in his upcoming book A Life Decoded.

The tome contains references to how Venter’s genome sequence might have affected his life, says Jan Witkowski, executive director of the Banbury Center at Cold Spring Harbor Laboratory in New York, who is reviewing the book.

Venter’s sequence also provides important new information about the human genome, say the researchers who picked apart the sequences belonging to both chromosomes in each of the 23 chromosome pairs found in the biologist’s cells, providing the first glimpse of the variation found within a single genome.

None of the previous sequencing efforts had distinguished between the two copies of each chromosome or even between DNA from different donors, add the researchers.

“What we were doing was mixing up alleles. We were creating Frankenstein versions of chromosomes,” Nature magazine quoted Samuel Levy, who led the study at the J. Craig Venter Institute in Rockville, Maryland, as saying.

For their research, the researchers were already armed with an additional 13 million sequences, 19 million generated from Venter’s own DNA during the first genome project, and fresh algorithms designed to pick sequences from different versions of the same chromosomes.

When the researchers looked at the variation within the genome, they found more than four million variations between the two sequences, including single nucleotide differences, sequence insertions and deletions, and differences in the number of copies of a given gene.

Levy says that about 44 per cent of Venter’s genes contained a genetic difference between copies found on each chromosome. Venter’s two sets of chromosomes differed by 0.5 per cent, suggesting that there might be seven times more DNA variation than previously expected, he added.

Edward Rubin, director of the Joint Genome Institute in Walnut Creek, California, said that the approach provided a clearer picture of the human genome. While the sequence gave a “statistical view” of the genome earlier, Rubin says that “in fact the genome is not statistical, it’s really a linear array of bases.”

Venter says that single genetic changes are unlikely to seal his fate.

“I take it very seriously. But most diseases are going to be some huge compilation of human factors and environmental factors,” he says.

Witkowski, though agrees to Venter’s propositions, says that reading about someone’s genome can strike an emotional chord.

“Somehow there’s a sense that when you tell people that sequence, you’re telling them in a very deep way about yourself. It’s like looking at their medical records,” he says. (ANI)