2010-3-22
FAITH LAPIDUS: This is SCIENCE IN THE NEWS, in VOA Special English. I'm Faith Lapidus.
BOB DOUGHTY: And I'm Bob Doughty. Today we talk about genes. They are parts of cells that control the growth of living things.
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FAITH LAPIDUS: Genetics, the study of genes, is gaining increasing importance. Genes can influence many things, from whom we look like to what we eat to possible treatments for diseases.
Recently, for example, two separate research teams reported sequencing the genomes of several patients. The teams identified the genetic structure of the patients. Those individuals suffer from diseases caused by mutations or changes in genetic material. By studying the order of the genes, the researchers found the causes of the disease.
This is the first time genomes of people suffering from disease have been completed. In the past, only healthy people have had their genomes fully sequenced.
Experts say the results of the studies may help medical researchers develop treatments especially designed for individual patients.
BOB DOUGHTY: One of the studies involved Richard Gibbs and James Lupski of the Baylor College of Medicine in Houston, Texas. They identified the genetic cause of a disease called Charcot-Marie-Tooth. The disease causes nerve problems in the hands and feet and muscle weakness. In this study, the patient was Doctor Lupski himself. The researchers found that he and three members of his family had two disease-causing mutations in one gene. That gene had earlier been linked to the disorder.
The second study involved researchers at the Institute for Systems Biology in Seattle, Washington. Leroy Hood and David Galas examined all the genes of four people in a family. Two children in the family each have two diseases caused by a single gene. The researchers also examined the genomes of the parents. That made it possible to identify the exact gene mutations that caused the diseases in the children.
FAITH LAPIDUS: The researchers were able to do their work because of the Human Genome Project. The project cost nearly three billion dollars, and was completed in two thousand three. Since that time, sequencing methods have greatly improved. Doctors hope that a patient may someday pay about one thousand dollars for a completed genome.
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BOB DOUGHTY: A chromosome is a piece of DNA, deoxyribonucleic acid, in the nucleus of a cell. Each chromosome contains many genes that direct the production of proteins needed by cells. Genes exist in plants, animals, human beings and even some viruses.
People have two copies of each gene. Most genes are the same for everyone. Less than one percent of genes differ from person to person. But these small differences make each person an individual, different from others. Identical twins, however, are developed from the same egg. Their genes are the same.
FAITH LAPIDUS: A nucleus in every cell surrounds genetic information with a membrane that protects it. The nucleus contains rope-like strands of DNA that carry the information. Scientists have long known that DNA includes different amounts of four chemical bases.
Genes tell every cell in an organism what qualities or characteristics it can develop. The DNA of the flowering azalea plant, for example, contains all the information that makes it an azalea. Human DNA carries the information that decides our heredity, the characteristics passed on to us by our ancestors.
Genes decide how and when each kind of cell will develop in differing organs. For example, genes direct formation of the fetus's brain at set times in a woman's pregnancy.
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BOB DOUGHTY: Gregor Mendel is known as the father of genetics. Yet he would not have called genetics by that name. Mendel was a Roman Catholic monk and teacher who lived in the nineteenth century. He studied the characteristics of pea plants. His experiments led him to develop laws of heredity. Most of those laws are still respected and used today.
Many developments in genetics have taken place since Mendel did his work. A half-century ago, for example, producing genetic copies of animals was only a dream of scientists. But then, new knowledge made cloning possible. In nineteen ninety-six, a sheep named Dolly became the first animal to be cloned. Researchers have also cloned cats, mice and pigs.
FAITH LAPIDUS: By the nineteen eighties, scientists were working to complete the genome of human beings. Their goal was to understand the structure or organization of human genes.
United States government agencies and international partners launched their efforts to sequence the human genome in nineteen ninety. James Watson was the first leader of the project. He had shared a Nobel Prize for his part in the discovery of the structure of DNA.
BOB DOUGHTY: In nineteen ninety-three, Francis Collins was named to lead the genome effort. The Human Genome Project published partial results in two thousand. Three years later, the completed version was announced. Craig Venter led another effort to complete the human genome at a private, not-for-profit laboratory. But he and Francis Collins say they were not competing. They have shared in the worldwide praise of their work.
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FAITH LAPIDUS: Discoveries in genetics have made possible many helpful developments. But they also have raised legal, moral and safety questions.
Organisms that are genetically modified, G.M.O.s, have had their genes changed to improve their characteristics. Supporters of one kind of G.M. cotton, for example, note evidence that it can help a plant resist insects and viruses. Supporters of G.M. foods say they can help feed an estimated three billion more people by the middle of the century.
BOB DOUGHTY: But G.M. food crops have opponents. Recently, Indian officials announced that no more G.M. eggplants would be grown for profit in the nation. The officials said they want more testing for safety. However, G.M. crops have been grown and used for thirteen years. And during that time, supporters say, there has been no sign of major health or environmental problems.
Nina Fedoroff is a plant genetics expert. She says G.M. crops are needed. She says people have shown unreasonable objections to new developments throughout history. Nina Fedoroff says unfair judgment is not unusual.
NINA FEDOROFF: "The only way that I can stay patient is to recognize that this is not unique to G.M. foods, and it is not new."
FAITH LAPIDUS: Doug Gurion-Sherman is with the Union of Concerned Scientists. He says he does not believe there is evidence of harm from G.M. plants. But he calls on government agencies for more tests and increased watchfulness over G.M. crops.
Genetic testing helps many people. Tests of DNA have helped release prisoners falsely accused of crimes. The tests sometimes reunite separated families and settle questions about who is the father of a child.
BOB DOUGHTY: Yet genetic testing also can raise moral, ethical and religious questions. For example, husbands and wives in some ethnic groups are tested for the possibility of having a child with Tay-Sachs. Genetic problems cause the disease. If the tests show a high possibility, a married couple must decide if they want to risk a pregnancy.
And, many women who are pregnant take tests to learn about the condition of the fetus. What if the fetus is found severely affected by a faulty gene?
FAITH LAPIDUS: Testing can show possibilities of sicknesses a person can face in later life. Suppose genetic tests show that you may someday suffer from a disease that robs you of your intelligence. What happens if this information reaches your employer or your insurance company?
The United States approved a law in two thousand eight to prevent unfair treatment. The Genetic Information Nondiscrimination Act bars insurance companies from rejecting people based on genetic test results. Under the law, employers are not to reject people seeking work because of their genetic information.
BOB DOUGHTY: Another question is who owns the right to genes. The United States has approved patent rights for some genetic sequences. This means a research center or health care company can control intellectual property rights to genes. The patent holder can demand payment for the right to its use.
Critics say such patents block progress against disease and development of new treatments. Courts are now considering cases against patenting genes.
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FAITH LAPIDUS: This SCIENCE IN THE NEWS was written by Jerilyn Watson. Our producer was Brianna Blake. I'm Faith Lapidus.
BOB DOUGHTY: And I'm Bob Doughty. Join us again next week for more news about Science in Special English on the Voice of America.