Germ Line Gene Therapy
Whether it is referred to by its scientific term syngamy or by the general term conception, the moment a sperm cell unites with an egg cell stirs, both in the scientist and the layperson, much awe and reverence. It is the point at which a new and unique genome is created. To some it is the instant a new person comes into existence. Such a union has been repeated for billions of years since its advent in the first, simple organisms. It is a means by which evolution can exert its influence. When the genetic material of two individuals combine in sexual reproduction, any variations between the two inherited sets of genes may result in offspring that are more or less suited to its environment. Human beings have come to a point in this process where we can now, to an extent, shape the environment to suit our needs.
The evolution of intelligence in our specie is the characteristic that has had the most profound impact on our planet and on us. This intelligence, among other things, allows us to understand and combat some genetic diseases. Inventions such as spectacles to correct our vision or drugs that fight heart disease and cancer have extended and improved the lives of individuals who, in a more Darwinian world, would have otherwise been eliminated by natural selection. Cheating this process, however, has allowed a multitude of genetic diseases such as Tay Sachs and hemophilia to propagate in our gene pool. But researchers are taking the field of medicine to a new frontier that promises to eliminate genetic diseases. New technology is being developed that will allow scientists to alter or replace defective genes in germ-line cells (egg and sperm cells). In a literal sense it will allow us to control the evolution of our specie as these alterations may be passed on from generation to generation. The implications are profound for the individual and for society. Above it all the specter of eugenics, the process of selected breeding to improve the human race, hovers and reminds us of the danger that such technology may create. But careful public deliberation should allay fears and allow us to develop an ethical framework that will guide society and the scientific community in any decision making process. It is in this regard that we should allow research in this field to continue as it promises more real benefits than imagined dangers.
For the past two decades, gene therapy promised to cure genetic disorders such as cystic fibrosis, sickle-cell anemia, and even cancer. Despite the progress of this technology, few have benefited. The problem is getting new genes into enough cells, and keeping them there long enough to do any good. Germ-line engineering promises to circumvent these difficulties. Through this technique, only one cell, a fertilized human egg (a germ cell), needs to be altered. After subsequent cell divisions and then implantation into the uterus, the cells that divide and grow will each have the alteration. Sharon Begley describes one scenario in her article, Designer Babies (Newsweek, November 9, 1998). At an in vitro-fertilization clinic a couple has an artificial human chromosome inserted into their fertilized egg. One of the genes on this chromosome will carry the instruction ordering cells to commit suicide. The embryo will be implanted into the mother's uterus and eventually a baby boy will be born. Some fifty years into the life of the genetically altered man he, like the men in his family before him will develop prostate cancer. However, Begley continues, The cell suicide gene will make his prostate cells self-destruct. The man, unlike his ancestors, will not die of the cancer. And since the gene that the doctors gave him copied into every cell of his body, including his sperm, his sons will beat prostate cancer too. The situation described is still far from being realized. But technology is moving along and its implications are already fully realized.
Begley's article reports on a recent symposium held at the University of California, Los Angeles. An advisory panel consisting of distinguished scientists set out to summarize the advances in the field of germ-line therapy and to discuss its implications. It was hoped that this