When future historians look at this
time period, its hard to say what they may select as our greatest
achievements. They may hold the computer chip or the steps taken on the
Moon as our greatest exploits. They may even consider nuclear fusion or
the Internet our most prominent success. An even greater feat may soon
overshadow them all. Two years ahead of schedule, the Human Genome Project
(HUGO) is set to attain its current goals by the year 2003.
It is unlikely that any other human
achievement has ever pulled together the resources and international cooperation
to such a massive degree. Researchers across the globe are pooling their
efforts to make publicly known the very instructions for human life itself.
The greatest aspect of HUGO is not only the information it provides, but
the responsibility and foresight of the projects goals. Project leaders
have realized the information they are unveiling is larger than the textbooks
it will fill. The genome project is actually a comprehensive series of projects
designed to assist a vast number of intellectual and even theological investigations.
The primary goal is, of course, to
sequence every nucleotide, all 3 billion, in the human genome. The means
of reliably finding the nucleotide sequence involves several steps. The
analyzed DNA is collected from blood and sperm samples. These samples are
taken from a pool of people, only 15 or so are actually used. Neither the
researchers nor the donors know whose donations are actually being used.
The genome is thus a conglomerate of these genetic samples and not one specific
individual. The differences between any individuals is minute in comparison
to the enormous similarities among individuals of a similar species. Even
the genetic blueprints of chimpanzees differ from humans by only 1-2% of
the nucleotides.
There
are several types of sequencing methods. The most widely used at this time
is the chain termination method. This method utilizes flourescently labeled
dideoxy nucleotides to interfere with the elongation of the strand by the
DNA polymerase. The dideoxy nucleotides lack a 3 OH group. Since this
is the site of attachment for the next nucleotide, competition of dideoxy
nucleotides with regular nucleotides will cause the chain to terminate at
random points during its extension. These dideoxy groups are flourescently
labeled, and a laser with a detection device can tell whether a given segment
ends in an Adenine, Thymine, Guanosine, or Cytosine nucleotide (A, T, G,
or C, respectively). These segments can be separated according to size.
The resolution is sensitive enough to allow researchers to detect the emission
and order of all of the flourescently labeled dideoxy nucleotides. Any segment
of DNA must be sequenced in this fashion about ten times to provide enough
information to allow the weeding out of erroneous results and produce a
very high quality sequence. Ten sequences leaves room for a single mistake
in ten thousand base pairs. In June, 2000, a low quality, 5-sequence draft
of the human genome was completed to provide a reference for researchers.
A second goal of the project is to
improve the sequencing technology itself. Such improvements will allow future
sequences of other organisms to be completed at a much faster and cheaper
rate. The cost of sequencing each nucleotide is approximately fifty cents.
Improvements in technology seek to cut this cost in half. Developments on
the horizon include microelectrochemical systems, rapid mass spectrometric
analysis, and single-molecule sequencing methods.
The introduction of the human genetic
sequence into modern genomics is another primary goal. Thoughtful concern
for how the sequence will be used at these early stages will streamline
efforts in the future to use the data. This aspect will be fulfilled by
establishing the sites of translation for every protein made in the body.
There may be as many as one hundred thousand of these gene producing sites
in the human genome. To find these sites, the correlating mRNA of a given
protein is isolated and reverse-transcribed back into complementary DNA.
Reverse transcription utilizes the same reverse transcriptase that enables
retroviruses to convert their RNA into DNA for insertion into the hosts
genome. This complimentary DNA (cDNA) can be used to associate and mark
the site of transcription on the original DNA. These sites are referred
to as Sequence Tagged Sites (STSs). STSs are then compiled to produce a
cytogenetic band map of the chromosome. Non-coding regions of DNA, methods
of mutating genes and the improvement of cDNA libraries will be investigated
as well.
Single-nucleotide polymorphisms (SNPs)
will also be investigated. Researching SNPs provides information on the
effect of altering specific nucleotides. Such information will allow researchers
to peer into, predict, and possibly correct, the exact nature of genetic
disorders.
Expanding the field of comparative
genomics is a goal of the Human Genome Project that will drastically help
improve the understanding of the human body. The complete genomes have been
found for several other organisms. The yeast, (Saccharomyces cerevisiae),
roundworm (Caenorhabditis elegans), fruit-fly (Drosophila melanogaster),
and archeon (Methanococcus jannaschii) have already been completed, but
none contain such complexity as that of the human genome. ) The vast amount
of research into the fruit-fly and mouse make the development of their genomes
of extremely beneficial. HUGO plans to have the mouse sequenced by 2005.
Ethical, Legal, and Social Implications
(ELSI) is a section of HUGO seeking the best means of introducing the genetic
technology into society, if such an introduction is even plausible. Issues
addressed in this category include the use of genetic information into health
care and even non-clinical applications. Investigations into religious and
philosophical are also being supported in an attempt to understand the ethical
implications involved in the study and manipulation of our own genes.
Other sections of HUGO look to the
future of genetics. The development of new technologies to implement and
investigate genetic data is of crucial importance for future research. The
training of future geneticists is of vital importance as well.
The completion or even partial completion
of the human genome and its corresponding STSs enables every function and
disorder of the human body to be analyzed at a genetic level. Such a level
of analysis provides the capacity to exact a great amount of good and bad.
With development of vectors to alter
the genetic makeup of an individual, it will soon become a relatively easy
procedure to correct genetic disorders. Vectors to correct the single base
error associated with hemophilia are under development now. The extent to
which similar vectors can be developed to cure the ailments of mankind is
virtually limitless. With the development of gene chips, potentially capable
of screening an entire genome in less than a day, it may be possible very
soon to screen and cure any of these possible defects even before the individual
is born.
There is also a great potential for
misuse of the genetic information revealed by the Human Genome Project.
A great challenge to modern day thinkers is first to determine what would
constitute a misuse of the information. Opinions tend to differ greatly.
Many people are appalled at the idea of changing someones genetic
makeup even to correct a "disorder." Others find nothing wrong
with changing the color of your unborn childs eyes on a whim.
It is no-longer unreasonable to imagine
a person, now in their twenties, to have the choice of genetically altering
their children to prevent hemophilia or grandchildren to produce a track-star.
Where should the line for correction be drawn? Is it wrong to make a person
with some preconception of who they should be? Are we eliminating the triumph
of the human spirit by destroying the very hardships and challenges necessary
to foster its development.
Society appears to be quite unprepared
to provide answers these questions. The science of movies and novels has
led us to believe the hardest philosophical decisions made in the twenty-first
century would be what color the hover car should be. Now that the power
of altering our very genes is approaching our grasp, we must ask if our
hearts are prepared to go where our minds are rapidly taking us.
Human Genome Project Web Site Links
Science
Magazine - Human Genome Project outlines
DNA
Sequencing - dideoxy method
Sanger
Centre - Overview of the Human Genome Project
Government
research - Great links to most Human Genome Project research facilities
The Sanger Center
- Mapping of chromosome 22 completed.
Chromosome
browser
Process
of DNA sequencing - acrobat document
ABC
radio interview - The Post-Genome-Era
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