Why is there no GENE THERAPY section in this BIOMEDICAL ETHICS area?
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Reply by Jack P. Freer, MD
This is an important area for discussion; thanks for raising the question. In order for readers to understand some of the ethical issues related to the important field of genetics, I will provide a rather lengthy explanation of some background material now, and develop these ideas further in future messages. There are two major categories of genetic therapy currently under investigation: somatic and germ-line. Understanding the difference is necessary to follow the ethical debate about such treatments.
A large number of personal traits (including personal physical features, personality characteristics, and illness susceptibility) are now understood to be under genetic control. That is to say, much of who we are is determined by the genetic information built into our cells at birth. In regard to diseases, this includes the typically "genetic" disorders (such as hemophilia and sickle cell disease), but also less well defined tendencies to develop cancers or Alzheimer's disease. Although we don't understand all the details concerning how these illnesses are made more likely by our genes, we continue to learn more with each passing day. Theoretically, it is possible to (someday) reveal a large amount of information about how how many many people are predisposed to various illnesses.
The basic mechanism of genetic information transfer is a two step process. We have two kinds of cells in our bodies: somatic cells and germ cells. The somatic cells are the vast majority of cells in our bodies and constitute the material which makes up most of our organs and tissues. Germ cells however, are quite different. They are the reproductive cells which are transferred from generation to generation and are located within our reproductive organs. They grow and multiply for the sole purpose of forming eggs and sperm cells to create new organisms. They also obviously contain the information about all the traits mentioned above (including susceptibility to illness), but don't affect THAT person. Rather, they affect his or her offspring (when the information is transferred to the child's somatic cells).
Once we understand how these traits are transmitted and cause disease, we can try to interrupt the process. We can start by blocking or otherwise offsetting the disease process implemented by the somatic (body) cells. So for example, in cystic fibrosis, an hereditary defect prevents cells in the respiratory and intestinal tract from secreting important substances. This results in digestive problems and very serious lung problems. The failure to produce normal respiratory secretions leads to serious lung infections, and ultimately to an early death. Now, by treating the somatic (specifically, lung) cells missing genetic material, the cells can function normally, and infections can be prevented. That person however, can still transmit the gene for cystic fibrosis to his or her child, because the germ cells have *NOT* been altered. Somatic cell therapy treats the patient before us NOW, but if we could treat the germ cells, we could eliminate the disease in future generations. In future message, we will discuss the Human Genome Project, germ cell therapy, and ethical issues related to this topic.
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Jack P. Freer, MD
JFreer@ubmedb.buffalo.edu
as416@freenet.buffalo.edu
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