Human genetic code cracked

Scientists have opened the "book of life," cracking the human genetic code, but medicine's brave new world could have sinister repercussions.

The deciphering of the 3.1 billion sub-units of human DNA by international scientists is set to revolutionise medicine, bringing new treatments for deadly diseases but also opening a Pandora's box of issues from "designer babies" to genetic discrimination for jobs or insurance.

The breakthrough announced yesterday ranks alongside the world-changing moments of science, from Galileo's space discoveries to the introduction of penicillin.

Describing the result as the most important map produced by humanity, President Bill Clinton said: "Today we are learning the language in which God created life.

"The code will revolutionise the diagnosis, prevention and treatment of most, if not all, human disease."

The unlocking of the specifications of the human species has already started a search for new technologies to identify faulty genes early so they can be replaced with normal versions.

Among the diseases which could be treated by attacking their genetic roots are Alzheimer's, Parkinson's, diabetes and cancer.

An international consortium of 1000 scientists, working for the publicly funded Human Genome Project, and its privately owned rival the Celera Genomics firm, announced it had deciphered 97 per cent of the human genetic code.

The head of the Human Genome Project, Dr Francis Collins, said the breakthrough would allow humanity to begin reading "our own instruction book."

What the scientists have discovered is a long read-out of the molecules, or nucleotides, that make up the rungs of the DNA ladder - named as As, Ts, Cs and Gs.

If printed on sheets of standard, letter-sized paper, the stack would reach the top of the 170m Metropolis building in downtown Auckland. It could take 100 years to read your own code.

But while medical cures could be some years away, ethicists warned humanity had to start grappling now with the implications.

An Auckland University senior lecturer in medical ethics, Dr Jan Crosthwaite, said history had shown humans' propensity for "tinkering" without realising where it could lead.

The splitting of the atom, a discovery with enormous potential for public good, was put to "amorally inadvisable" use.

Already in America there have been warnings that genetics could be used to identify people by race. In New Zealand, that could include a test to determine if a person was Maori and therefore eligible for a Treaty of Waitangi settlement.

One of the most difficult ethical areas is antenatal genetic screening, where tests on unborn children could detect whether the unborn child has the potential for debilitating diseases.

In Britain, the Royal Association for Disability and Rehabilitation said it could lead to greater testing of pre-implantation embryos to ensure babies had "desirable attributes."

The new information could be used by health insurers to identify and refuse cover to people with genetic dispositions towards costly illnesses and by employers to screen potential staff for genetic flaws.

Professor Bob Blank, expert in biomedical policy at Canterbury University, predicted that there could be an explosion of new screening tests for health behaviour possibly even within the next five years.

"Certainly, employers are going to want to know if you have the potential for a heart attack or other health risks. They don't want to put a lot of training and money into you if you're going to be dead in a year.

"This gives us a whole set of new information to diagnose an embryo to see if it's worth keeping it alive.

"If we get to the stage of gene therapy, then the parents would have the option of having a new gene put in to replace the gene that was a problem.

"It raises all kinds of questions of how much we should be manipulating the genes of future generations."

This month, New Zealand health insurers said they would hold off introducing DNA tests for clients until British insurers had decided whether to use tests, which could mean bigger premiums for people with a high genetic risk of chronic conditions.

Dr Collins has called for new laws to prevent "genetic discrimination" to make sure no one is deprived of health insurance or a job if tests revealed a propensity to cancer or heart disease.

- STAFF REPORTERS, REUTERS

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