The Ethical Considerations of Genetic Screening

Ever since Watson and Crick deciphered the biological code of life, scientists have been busy unraveling the mysteries of life. A recent development in the area of genetic research has been the Human Genome Project (HGP). The HGP is a massive international effort to map and sequence the entire human genetic code. The primary goal of this research is to link certain diseases with abnormal genes that may be possessed by certain people. This would allow researchers the ability to screen individuals for certain diseases. This has already been a success with a number of conditions. PKU is a condition that causes severe retardation in children if nothing is done to prevent it, but by genetically screening the infants, doctors are able to tell who has the disease (Davis 1990). By simply altering the diet of these children, the mental retardation effects of the disease can be prevented. In addition, diseases such as Huntington’s disease, breast cancer, and muscular dystrophy are presently being screened for in humans (Jaroff, 1996).

How researchers are able to screen for genes

New developments have given researchers the ability to decipher the genetic code of organisms. Some of the techniques that researchers use are RFLP (restriction fragment length polymorphism) analysis and DNA probes. RFLP analysis utilizes enzymes from bacteria that are thought to be used as defense mechanisms against invading viral DNA. The enzymes fragment foreign DNA at specific locations depending on the base sequence (Griffiths, 1996). In order to analyze an organism’s genome a researcher will add a certain restriction enzyme to DNA. This produces small restriction fragments of DNA that vary in length. Electrophoresis is then used to separate out the various fragments of DNA. This is accomplished by subjecting the fragmented DNA to an electrical charge after it has been placed onto an agarose gel plate. Due to differences in length, the DNA restriction fragments will be separated in the gel plate.

Another useful tool for scientists has been the DNA probe. A DNA probe is a piece of DNA that binds to certain sequences of the hosts DNA (Devore, 1998). The probe is able to do this because the DNA strand of the probe only binds to the appropriate DNA with a complementary sequence. Scientists label the probe with florescent markers or radioactive markers so that the gene of interest can be visualized. Often probes are used in conjunction with RFLP. After the organisms genome has been fragmented and electrophoresed, an absorbent membrane is placed over the gel and the DNA bands are "blotted" onto the membrane (this technique is called Southern Blotting).