Researchers announced in June 2000 that they had finished a "rough draft" of the human genome — the genetic code that controls much of our development and illnesses. The code consists of 3 billion "letters" that make up the DNA script in human cells. What might these letters spell?

Not long ago, deciphering the complex code embedded in human DNA was a dream to genetic researchers. On June 26, two competing teams of these researchers—one working for the U.S. government and another for a private company—excitedly shared the news that they had finished mapping that code ahead of schedule.

The scientists also reported that they had identified the proper sequence for almost all of the code. They will spend the next two years filling in any missing pieces or correcting mistakes.

The U.S. Human Genome Project began in 1990. Its ambitious plan was to identify and map every gene on all 23 human chromosomes. This complete set of genetic instructions for an individual organism is called a genome.

This unprecedented map promises to increase knowledge about genetics and to discover the source of some 4,000 known human genetic disorders, as well as the means of treating countless other diseases and conditions.

The Human Genome Project has already produced much valuable information. Scientists have identified and isolated genes linked to kidney disease, different forms of cancer, high-blood pressure, dwarfism, and Down syndrome. With that knowledge in hand, it is only a matter of time before someone determines how to correct the gene or block its harmful effects on the body.

• Read about the most recent developments in this CNN.com article:

"Rough map of human genome completed"

The human genome can be thought of as your master blueprint—the design specs needed to reproduce you in every detail. It describes all of the different types of cells in your body and all of their functions over the course of your lifetime. The genome is encoded in the nucleus of every single cell in your body. It consists of the tightly coiled threads of DNA and the genes they contain.

In order to decode the human genome, researchers first take apart human DNA. The decoding process is basically one of identifying the pieces and arranging them like pieces of a puzzle. There are several steps in decoding the human genome:

1. Sequencing: Researchers identify the chemical base pairs that make up each gene and put them in the proper order. (There are four different though similar chemicals that make up genes: adenine, thymine, guanine, and cytosine. They are commonly abbreviated to: A, T, G, and C.)
   
   

2. Assembling: Researchers assign genes to the correct chromosomes and put the genes in the correct order.
   
   

3. Annotating: Researchers identify the function of the gene. It is in this stage that genes are linked to diseases and genetic malfunctions.
   
   

How big is the human genome these researchers are studying? Take a look at this analogy from the official Human Genome Project Web site:

To get an idea of the size of the human genome present in each of our cells, consider the following analogy: If the DNA sequence of the human genome were compiled in books, the equivalent of 200 volumes the size of a Manhattan telephone book (at 1,000 pages each) would be needed to hold it all. It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in one person's genome sequence. This is calculated on a reading rate of 10 bases per second, equaling 600 bases/minute, 36,000 bases/hour, 864,000 bases/day, 315,360,000 bases/year.

The end goal for researchers is the creation of new drugs and treatments to attack, cure, or prevent diseases caused by defects in genetic material. Knowing how the human cells work may also make it possible to create little living "factories" capable of producing any human protein.

Scientists have rushed to apply the data already available to research in disease identification and prevention, and to the creation of new medicines and treatments.

One such treatment is gene therapy, in which doctors try to replace a faulty gene with a healthy one. This technique has been attempted in treating cystic fibrosis, hemophilia, and different immune system disorders. In April, French researchers announced promising results in their gene therapy trials in treating the immunodeficiency syndrome known as "bubble boy" disease. However, gene therapy has had its controversy, with several research programs shut down after patients died from the experimental treatments.

The biggest question remaining is whether or not the public is ready for what comes next. Where will this new knowledge about what makes a human being take us? A person's entire genetic history—and future—could potentially be revealed in an analysis of a bit of hair, a drop of blood. Once known, what becomes of that information?

Consider these thought-provoking questions about what is good or bad, right or wrong, in medical research, taken from field of bioethics:

• Once genetic tests for various conditions are available, will they be available to everyone? Will your insurance company or HMO pay for testing? Who will pay for testing those persons who are not insured?
  

• Will a person be denied health insurance because of something revealed in his genetic tests or in the genetic tests of his immediate family?
  

• Is it a good thing to develop a genetic test for diagnosing a disease for which there is no cure?
  

• Will employers or potential employers use genetic testing results against an employee or potential employee?
  

• What protections are there to guarantee that a person's genetic profile remains private?
  
  

Can you think of any additional ethical concerns with human genome research?

Learn More

• For more on the ethics questions surrounding breakthroughs in genetic research, see the Riverdeep story, "Dilemmas of the New Genetics."
  

• See the Teaching the News article, "Human Genome Project Finishes Sequencing First Human Chromosome."
  

 

The following Riverdeep activities can help you understand the concepts involved in the Human Genome Project. (The activities require Logal Express. Get a free trial subscription.):

More Links

• Read more about DNA, genes, and chromosomes in this article from Johns Hopkins University.

• Listen to this All Things Considered interview with Dr. Francis Collins, director of the National Human Genome Research Institute, as he discusses how knowledge from the mapping of genes is already being applied today. (Requires RealPlayer. Download now.)
  
  

• In this National Public Radio report, correspondent Richard Harris reports on industry efforts to patent data from the human genome. (Requires RealPlayer.)

Related Resources

• Concentrating on individual scientists and research, The Human Genome Project: Cracking the Code Within Us, is a personal look at the science behind the Human Genome Project and its possible benefits for future human health.