Introduction - The Human Genome Project
National Center for Human Genome Research, National Institutes
of Health. "New Tools for Tomorrow's Health Research." Bethesda, MD:
Department of Health and Human Services, 1992.
Since the beginning of time, people have yearned to explore the
unknown, chart where they have been, and contemplate what they have
found. The maps we make of these treks enable the next explorers to
push ever farther the boundaries of our knowledge - about the earth,
the sea, the sky, and indeed, ourselves. On a new quest to chart the
innermost reaches of the human cell, scientists have now set out on
biology's most important mapping expedition: the Human Genome Project.
Its mission is to identify the full set of genetic instructions
contained inside our cells and to read the complete text written in
the language of the hereditary chemical DNA (deoxyribonucleic acid).
As part of this international project, biologists, chemists,
engineers, computer scientists, mathematicians, and other scientists
will work together to plot out several types of biological maps that will
enable researchers to find their way through the labyrinth of
molecules that define the physical traits of a human being.
Packed tightly into nearly every one of the several trillion body
cells is a complete copy of the human "genome" - all the genes that
make up the master blueprint for building a man or woman. One hundred
thousand or so genes sequestered inside the nucleus of each cell are
parceled among the 46 sausage-shaped genetic structures known as
New maps developed through
the Human Genome Project will enable researchers to pinpoint specific
genes on our chromosomes. The most detailed map will allow scientists
to decipher the genetic instructions encoded in the estimated 3
billion base pairs of nucleotide bases that make up human DNA.
Analysis of this information, likely to continue throughout much of
the 21st century, will revolutionize our understanding of how genes
control the functions of the human body. This knowledge will provide
new strategies to diagnose, treat, and possibly prevent human
diseases. It will help explain the mysteries of embryonic development
and give us important insights into our evolutionary past.
The development of gene-splicing techniques over the past 20 years has
given scientists remarkable opportunities to understand the molecular
basis of how a cell functions, not only in disease, but in everyday
activities as well. Using these techniques, scientists have mapped out the genetic
molecules, or genes, that control many life processes in common
microorganisms. Continued improvement of these biotechniques has
allowed researchers to begin to develop maps of human chromosomes,
which contain many more times the amount of genetic information than
those of microorganisms. Though still somewhat crude, these maps have
led to the discovery of some important genes.
By the mid-1980s, rapid advances in chromosome mapping and other DNA
techniques led many scientists to consider mapping all 46 chromosomes in
the very large human genome. Detailed, standardized maps of all human
chromosomes and knowledge about the nucleotide sequence of human DNA
will enable scientists to find and study the genes involved in human
diseases much more efficiently and rapidly than has ever been
possible. This new effort - the Human Genome Project - is expected to
take 15 years to complete and consists of two major components. The
first - creating maps of
the 23 pairs of chromosomes - should be completed in the first 5 to 10
years. The second component - sequencing the DNA contained in all the
chromosomes - will probably require the full 15 years.
Although DNA sequencing technology has advanced rapidly over the past
few years, it is still too slow and costly to use for sequencing even
the amount of DNA contained in a single human chromosome. So while
some genome project scientists are developing chromosome maps, others
will be working to improve the efficiency and lower the cost of
sequencing technology. Large-scale sequencing of the human genome
will not begin until those new machines have been invented.
Why do the Human Genome Project?
Most inherited diseases are rare, but taken together, the more than
3,000 disorders known to result from single altered genes rob millions
of healthy and productive lives. Today, little can be done to treat,
let alone cure, most of these diseases. But having a gene in hand
allows scientists to study its structure and characterize the
molecular alterations, or mutations, that result in disease. Progress
in understanding the causes of cancer, for example, has taken a leap
forward by the recent discovery of cancer genes. The goal of the Human Genome Project is
to provide scientists with powerful new tools to help them clear the
research hurdles that now keep them from understanding the molecular
essence of other tragic and devastating illnesses, such as
schizophrenia, alcoholism, Alzheimer's disease, and manic depression.
Gene mutations probably play a role in many of today's most common
diseases, such as heart disease, diabetes, immune system disorders,
and birth defects. These diseases are believed to result from complex
interactions between genes and environmental factors. When genes for
diseases have been identified, scientists can study how specific
environmental factors, such as food, drugs, or pollutants interact
with those genes.
Once a gene is located on a chromosome and its DNA sequence worked
out, scientists can then determine which protein the gene is
responsible for making and find out what it does in the body. This is
the first step in understanding the mechanism of a genetic disease and
eventually conquering it. One day, it may be possible to treat
genetic diseases by correcting errors in the gene itself, replacing
its abnormal protein with a normal one, or by switching the faulty
Finally, Human Genome Project research will help solve one of the
greatest mysteries of life: How does one fertilized egg "know" to give
rise to so many different specialized cells, such as those making up
muscles, brain, heart, eyes, skin, blood, and so on? For a human
being or any organism to develop normally, a specific gene or sets of
genes must be switched on in the right place in the body at exactly
the right moment in development. Information generated by the Human
Genome Project will shed light on how this intimate dance of gene
activity is choreographed into the wide variety of organs and tissues
that make up a human being.
Go to next story: Ethical issues of the Human Genome Project?
See Graphics Gallery:
Comparative Scale of Mapping
See the Human Genome Program web site at the Department of Energy
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