Questions & Answers About Human Genetic Code

Some questions and answers relating to today's announcement that scientists and researchers have virtually completed a rough draft of the human genetic code:

  • Do genes determine everything about us? Genes and environment work together to shape who we are. Because environment includes everything we experience and come into contact with from conception through death, it also plays an awesome and extremely complex role.
  • What is a gene? Even scientists disagree on exactly how to define a gene. Generally, a gene is a sequence of DNA that codes for a single protein. Proteins do the work of the body, building structures and catalyzing biochemical reactions.
  • How many genes are there? Because what scientists announced Monday is basically a string of 3 billion letters, not even scientists know how many genes there are. In a betting pool set up recently by one scientist, estimates ranged from about 34,000 to 140,000.
  • How genetically similar are we to one another? Individual humans share 99.9 percent of their DNA. That means that of the 3 billion letters in the human genetic code, each of us differs in about 300,000. Remarkably, those variations are scattered throughout the species without regard to what we think of as race.
  • How genetically similar are we to other species? Scientists have been amazed at how genetically similar humans are to other species. Humans share 80 percent of their genes with mice and about 99 percent of their DNA with chimpanzees. That means chimps are more closely related to humans than to gorillas.
  • Will this lead to a cure for cancer and other serious diseases? Virtually every disease has some genetic cause. Some are simple misspellings that may be compensated for by drugs or corrected with gene therapy, a technology that is still in its infancy. Others diseases, such as schizophrenia, are processes set off by multiple unknown genes that interact in complex ways. As scientists gain more knowledge about genes, they will develop new treatments based on that knowledge. The outlook is especially good over the next few decades for some cancers and Alzheimers disease.
  • Will anybody be able to use my genetic information against me? There are great concerns that genetic technology will be used to discriminate against people in employment, insurance coverage and other areas. People also worry that the discovery of a ``violence gene'' could be used to deny the civil rights of individuals based on their perceived potential to commit crimes in the future. Although President Clinton recently signed an executive order forbidding federal employment discrimination on the basis of genetics and Congress is considering legislation, many of these issues remain unresolved.
  • Why all this fanfare if the job won't be finished for another two years? In their experience cataloging the genes of dozens of other species, scientists have learned that the last few letters of code are the toughest. Monday's announcement covered 99 percent of the genome, leaving only a few gaps and regions of uncertainty. The remaining 1 percent will take another year or two to complete. But for practical purposes, the human genome is ready to use. Later this year scientists will publish a paper announcing that fact, and hold a conference to share everything they know about how the genes work.

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