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First Human Chromosome Mapped by Scientists

From the WebMD Archives

Dec. 1, 1999 (Washington) -- An international team of scientists Wednesday announced the achievement of a biomedical milestone -- the unlocking of the DNA code of an entire human chromosome. Collaborating researchers in the U.S., Japan, and Great Britain celebrated the 'sequencing' of chromosome 22.

There are 23 paired human chromosomes, microscopic bodies that are made up of genes. Genes carry our hereditary information. Together, the chromosomes make up the human genome. Carried inside each of our cells, the genome includes all of our basic biological instructions.

Under the international auspices of the Human Genome Project, scientists expect to complete mapping a "rough draft" of the entire human genome by next spring. They believe they will finish the entire sequence by 2003.

Researchers are enthusiastic about the upcoming genome map -- and the current 'downpayment' of the chromosome 22 sequencing. Richard Wilson, PhD, one of the scientists who helped unravel the chromosome, likened the new findings to releasing the "first volume of the human encyclopedia."

Peter Little, a biochemistry professor at London's Imperial College, tells WebMD, "[The genome sequence] is going to tell human beings for the first time what they're made of. It's going to take three years to write the book. This is just the first chapter of it."

Little says, "There are books which change the way human beings think about themselves. The last great book like that was [Charles Darwin's] The Origin of Species. [The human genome sequence] is going to be another such book."

The journal Nature, which is publishing the chromosome 22 findings in its Dec. 2 issue, dramatized the achievements with its cover art -- images of microscopic genetic material blended with Michelangelo's Sistine Chapel painting of the nearly joined hands of God and Man.

Francis Collins, MD, director of the National Institutes of Health's (NIH) National Human Genome Research Institute, exulted, "This is like a dream come true for the gene disease hunter."

Chromosome 22 is believed to be involved in the workings of the immune system, childhood heart disease, schizophrenia, mental retardation, various birth defects, and cancers such as leukemia.

Bruce Roe, PhD, a University of Oklahoma scientist who helped decode the chromosome, says, "Now we can begin to understand where genes are located on the chromosomes, how they express themselves, how deletions that give rise to disease-causing mutations occur, and how chromosomes are duplicated and inherited."

The NIH estimates that the human genome contains a total of about 80,000 genes. Scientists have pinpointed 545 genes in chromosome 22. Their sequence includes, however, 11 unanalyzable areas. Scientists know the size of these regions and where they are located. But those gaps, about 3% of the total chromosome, may contain as many as 300 additional genes.

The challenges are only beginning for further understanding our genetics. Little tells WebMD, "Our bodies are so incredibly complicated, that what we have to do is to simply to find out how all these hundred thousand different proteins [genes] operate together to make a human being. And that's going to keep us going for another million years."

NIH Director Harold Varmus, MD, tells WebMD, "You don't solve everything by looking at the genes themselves. It's too simplistic to say one gene, one disease." He notes, "There are many different forms of breast cancer caused by different mutations of different genes, and we still don't know which of those [genes] is the most vulnerable."

According to Varmus, "You might have a diagnostic [genetic] test, a risk assessment, that may be very, very powerful. But it may be much more difficult to translate that information into treatment for the disease."

Another issue is public access to the genetic maps. A private firm, Celera Genomics, is competing with the Human Genome Project to finish sequencing the human genome.

Could a company take patent control of this information? "Intellectual property history here is rather primitive," Varmus acknowledged.

The genome project is committed to full and immediate public disclosure of its findings. According to Rowe, "We've set a new paradigm for biomedical research." Little tells WebMD, "The human genome is too important to be owned by a company."

But Varmus confirmed that collaboration talks are underway between Celera and public genome scientists.

 

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