The Human Genome:
A genome is all the Genes and the DNA in an Organism. Genes carry vital
information for making all the proteins required by an organism. These proteins
determine how the organism looks, how well its body metabolizes food or fights
infection and sometimes even how it behaves.
DNA is composed of four types of chemical bases, Adenosine, Thymine,
Cytosine, Guanine (A,T,C,G) that repeat billions of times throughout the genome
along the DNA strands. The human genome has 3 billion pairs of bases.
The particular order of As, Ts, Cs and Gs is extremely important. The order
dictates all of life’s diversity and whether an organism is human or not.
In 1987, the US Department Of Energy(DOE) felt that understanding human genome was
as essential to the progress of medicine as human anatomy was to the then state of
medicine. A project called ‘The Human Genome Project’ was formally announced in
1990 by the DOE and the US National Institutes of Health (NIH) through its National
Human Genome Research Institute (NHGRI). It was not meant to study the genome of
every individual on this planet but of a few donors.
The Human Genome Project:
It began in October 1990 and was originally planned to last 15 years, but rapid
technological advances accelerated the completion date to 2003. The project cost was
estimated at about 2.7 billion dollars (FY 1991 dollars). The project was headed by Ari
Patrinos of the DOE and Francis Collins of the NHGRI. Apart from the US, various other
countries like China, France, Germany, Japan and the UK participated in it. The HGP not
only studied the makeup of human genes but also those of several non-human organisms.
These include the common human gut bacterium Escherichia coli (E. Coli), the fruit fly
and the laboratory mouse.
Its main goals were to
Identify all the human genes (approximately 20,000 to 25,000) from both a
physical and functional standpoint.
Determine the sequences of the 3 billion chemical base pairs that make up human
Store this information in databases (GenBank) available to anyone on the
Improve tools for data analysis.
Transfer related technologies to the private sector. It catalyzed the multi-billion
dollar US biotech industry and fostered the development of new medical
Address the Ethical, Legal and Social Issues (ELSI) that may arise from the
project. About 5% of the annual budget was dedicated to this purpose.
The data obtained from this project helps in administering genetic tests that can
show predisposition to a variety of illnesses like breast cancer, liver diseases and
so on. This data can also be used to develop preventive medicine.
It will facilitate medical advances in areas of clinical interest. Genome maps have
aided the researchers in identifying the gene responsible for various genetic
disorders like Alzheimer’s disease. Researches could use this knowledge to even
replace the defective gene through gene therapy.
A spin-off program called the Microbial Genome Program sequenced the
genomes of bacteria useful in energy production (bio-fuels) and environmental
Helps us in assessing risks caused by exposure to radiation and other mutagenic
Helps us in understanding human evolution and the common biology we share
with all of life.
DNA Forensics for identification of individuals.
Helps us in developing disease, drought resistant crops. For example, by
analyzing the genome of solanum tuberosum (White Potato), we can develop
drought, disease resistant potato seeds.
Though the project was announced to be complete in April 2003, studies continued and
the complete sequence of the last chromosome (Chromosome 1) was announced in 2006.
Also, there are a few other areas of the genome that are yet to be completely sequenced.
These include the centromeres (centers of chromosomes) and the telomeres (ends of
chromosomes). Due to their high repetitive DNA sequences, current technology isn’t
adequate to sequence them. We can say that more than 90% of the genome has been
sequenced so far. With the advent of new technologies, the remaining areas will be
sequenced sometime in the near future.
Two other spin-off projects that are worth mentioning here are the HapMap and the
ENCODE (Encyclopedia Of DNA Elements ) projects. The DNA sequence of any two
people is 99.9 percent identical. The small variation, however, may greatly affect an
individual's disease risk. The HapMap tool will enable researchers find those genetic
variations that affect one’s health and his response to drugs, environment. The ENCODE
project aims to identify all the functional elements in the human genome sequence. It will
identify the precise location of all the protein encoding and non-protein encoding genes
of the genome.