Scientists Find Human Genome Full of Surprises

Fewer genes, where they originated, how little we differ from other organisms and new drug targets are just a few of the surprises revealed in the human genetic code that will be published on Monday, February 12.

The human genome, or book of humankind, is a treasure chest of information about humans -- how we evolved, what makes us different and how much we share with other life forms.

The complex pairings of the 3.1 billion letters of DNA that make us humans is difficult to comprehend but the scientists around the globe who are deciphering the code say it will dramatically increase knowledge of ourselves.

"We are confirming Darwin -- that is the most useful take home message from this," said Sir John Sulston, who is spearheading the British end of the Human Genome Project.

"It is the unity of life, or Nature being conservative, or the idea of the Blind Watchmaker -- the notion of evolution as a constant reworking or random recombining of parts," he added.

The Human Genome Project, a consortium of scientists from the United States, Britain, Japan, France, Germany and China, will publish the initial sequence of the human genome in the science journal Nature on Monday.

A similar sequence compiled by Celera Genomics Inc , of Rockville, Maryland, will appear in the journal Science.

LADDER OF COMPLEXITY

One of the biggest surprises has been the number of genes in humans. The estimated 30,000-40,000 genes is far below previous predictions which ranged from 60,000-100,000.

Humans also share many genes with other organisms -- roughly half with the fruitfly and worm. Scientists believe the key to the differences between humans and worms is the functions of some human genes and the proteins they control.

"We know that as we move up the ladder of complexity from the single cell creatures, through small animals like worms and flies, and up to us, what we are adding on is control genes," Sulston explained.

"We are not adding so many new genes performing new functions -- what we are doing is to increase the variety and subtlety of genes that control other genes."

Researchers have to understand the basic set of instructions and how growing bodies interpret them to make a human being.

The number of potential new drug targets was also a big find. Instead of just 483 targets, there could be thousands of new destinations for medicines and drug to relieve illness and disease.

Scientists are already searching for new targets for asthma, Alzheimer's and depression.

Another surprise in the genome was that hundreds of genes seems to have come from bacteria, although scientists don't understand how it occurred.

So far 1,778 disease genes have been found and some chromosomes carry more mutations that cause disease and sickness than others. Males carry the most mutations.

When scientists announced the completion of the rough draft of the human genome last June, they thought 97 percent of human DNA was so-called "junk" DNA, without any important function.

But a closer look has led them to believe that "junk" DNA does has functions, one of which may be to move genes around.

In addition to genetic disease, the knowledge of human biochemistry that is contained in the human genome could hold new insights into tackling infectious diseases such as AIDS and tuberculosis.

"We can now start seriously investigating how it is that humans, who we think are so complex, can manage with only a relatively modest number more genes than worms and flies," said Martin Bobrow, a professor of medical genetics at Cambridge University.






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