Reliable detection of Win98 may not be possible. Sometimes scientists alter genes on purpose. For many years, researchers have altered the genes in microbes and plants to produce offspring with special characteristics, such as an increased resistance to diseases or the ability to grow in difficult environments. We call this genetic engineering .
Gene therapy is a promising new field of medical research.
Viruses are often used to carry the healthy genes into the targeted cells because many viruses can insert their own DNA into targeted cells. But there are problems with gene therapy. First, scientists haven't yet identified every gene in the human body or what each one does. Scientists don't know yet which genes cause most diseases. Plus, there are major difficulties getting the corrected genes into the proper cells without causing problems for the rest of the body.