Book of life is not a secret anymore

Book of life is not a secret anymore
PALLAVA BAGLA

NEW DELHI, FEBRUARY 11: Six months after the hype, the `book of life' is public. Last year the American scientists had stunned the world by announcing that they had completed sequencing the entire human genome. Now, the entire genome sequence has been published in a special issue of the American journal, Science.

It is the handiwork of a team led by maverick American scientist J. Craig Venter, chief of Celera Genomics who worked with his team of 282 scientists including at least of 15 scientists on Indian origin.

This `book of life', which has a length of about 2.91-billion base pair or what can also be equated to individual alphabets, accurately covers 95 percent of the genome, and the sequence sets the total number of human genes somewhere between 26,383 and 39,114, actually much smaller number than what people were expecting it to be.

Every person on earth shares 99.99 percent of the same genetic code. In fact, people from different racial groups can be more genetically similar than individuals within the same group. The human genome sequence is available free to any one who visits the website of Science at www.sciencemag.org.

The completed human genome sequence is expected to promote medical advances such as diagnostic tests, pharmaceuticals that reflect individual genetic variations, and perhaps gene therapies targeting segments of code responsible for disease. Single nucleotide polymorphisms (SNPs) or variations of a single alphabet in the book of life will help scientists identify the basis of many genetic diseases, and therefore provide targets for new treatments.

Though the completed sequence is estimated to have an average sequencing accuracy of 99.96 percent. Venter's research group cautions that human health, behavior and characteristics are influenced by many factors. Genetic information must therefore be used wisely.

``This stunning accomplishment, representing the most accurate human genome sequence ever completed, offers new and exciting prospects for targeting new medical improvements,'' said Science Editor-in-Chief Donald Kennedy. ``It can tell us much about our place in the diverse panorama of life.''

Interestingly, also revealed are vast stretches of desert-like regions, where the human genome sequence contains relatively few or no protein-coding genes. About one-fourth of the genome could be considered deserts, with lengthy gene-free segments. ``Genes exist largely in islands or clusters separated by large deserts millions of base pairs in length that have few or no genes,'' the paper concludes.

``There are no `good' genes or `bad' genes, there are merely networks that exist at various levels and at various connectivities, and at different states of sensitivity to perturbation,'' concludes Venter, Celera's president and chief scientific officer. ``The notion that one gene equals one disease, or that one gene produces one key protein, is flying out the window.''

``This assembly of the human genome sequence is but a first, hesitant step on a long and exciting journey towards understanding the role of the genome in human biology,'' the Celera group concludes. ``There are two fallacies to be avoided: determinism, the idea that all characteristics of a person are hard-wired by the genome; and reductionism, that now the human sequence is completely known, it is just a matter of time before our understanding of gene functions and interactions will provide a complete causal description of human variability.''

In the future, they wrote, ``The real challenge of human biology, beyond the task of finding out how genes orchestrate the construction and maintenance of the miraculous mechanism of our bodies, will lie ahead as we seek to explain how our minds have come to organise thoughts sufficiently well to investigate our own existence.''

The Celera team obtained DNA samples from five people: three women and two men. This group included one African-American, one Asian-Chinese, one Hispanic-Mexican and two Caucasians.