May 23, 2005 Gene therapy. The concept is simple: replace a defective gene with a new one. But it is hard to implement. First, a new gene must be put into the genome without disturbing what is there, and second, it must be expressed properly. Not surprisingly, the DNA of an organism is difficult to get at. Proper insertion and long-term expression turned out to be much trickier than anyone had suspected. Nature has a mechanism to move DNA, called a virus. But viruses have their own agenda, so to speak, and that is where the problems start. We look at the tortured history of this technology and the companies that are using it to fight disease...
