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Human genome sequence completed

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Although DNA dictates everything a cell does, the purpose of most DNA is not yet known. What is known is that changes in the DNA can lead to illness, to disease and to more subtle things, such as how the body responds to various substances.

Decoding DNA is expected to lead to enormous improvements not just in the diagnosis and treatment of disease and illness, but also in new sources of energy, healthier crops and livestock --even improvements in criminal investigation and detection.

LONDON, England (Reuters) -- Scientists have completed the finished sequence of the human genome, or genetic blueprint of life, which holds the keys to transforming medicine and understanding disease.

Less than three years after finishing the working draft of the three billion letters that make up human DNA and two years earlier than expected, an international consortium of scientists said on Monday the set of instructions on how humans develop and function is done.

"We put out the draft sequence as a way of getting it out to scientists as quickly as we could. It gives them something to work with and get going, but the aim was always to generate a reference sequence for the human genome," Dr Jane Rogers, head of sequencing at the Wellcome Trust Sanger Institute, said.

"It's a bit like moving on from a first attempt demo music tape to a classic CD."

The Human Genome Project has already aided scientists in discovering a mutation that causes a deadly type of skin cancer and accelerated the search for genes involved in diabetes, leukaemia and childhood eczema.

The completed sequence will help scientists to identify the 25,000-30,000 genes in humans, including those involved in complex diseases such as cancer and diabetes.

Researchers from 120 countries have downloaded information which has been freely available on the Internet since the rough draft was announced in June 2000.

Exciting chapters

"We shouldn't expect immediate major breakthroughs but there is no doubt we have embarked on one of the most exciting chapters of the book of life," Professor Allan Bradley, director of the Wellcome Trust Sanger Institute, said in a statement.

The Institute sequenced nearly one-third of the genome.

Scientists in the United States, France, Germany, Japan and China have also worked on the publicly-funded Human Genome Project.

The human genome has already revealed some of its secrets. There are far fewer genes than scientists had expected and proteins, which build tissues and regulate the body's function, are much more complex than they thought.

"The nematode worm has about 17,000 genes, so we haven't really got very many more than a small worm. But we manage to construct a great variety of proteins from those genes. Understanding how that happens is the next challenge," Rogers said.

The finished sequence is expected to spark a boom in genomic research in the pharmaceutical industry and to underpin biomedical research in the coming decades.

New treatments, customised drugs to individual genetic profiles and earlier diagnosis of disease are expected to be among the initial benefits of the human genome sequencing.

Scientists have already identified more than 1.4 million SNPS, single nucleotide polymorphisms - variations in the three billion letters of the human genetic code.

SNPS are single changes in the arrangement of those letters that make people different. They hold the key to susceptibility to illnesses such as cancer, diabetes and heart disease and individual responses to medication.

By looking at different subsets of the genome of several people and comparing the results, scientists hope to identify specific DNA variations that cause propensity for a certain disease as well as its genetic basis.

"Completing the human genome is a vital step on a long road but the eventual health benefits could be phenomenal," Bradley said.

Copyright 2003 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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