Genetic Screening Essays - Medical Genetics,

Genetic Screening Genetic screening, also known as preimplantation genetic diagnosis (PGD), is a newly emerging technology that has brought with it much controversy. PGD involves the in vitro fertilization of an embryo. ?The embryos are allowed to develop to a 6 to 10 cell stage, at which point one of the embryonic cells is removed from each embryo and the cellular DNA is analyzed for chromosomal abnormalities or genetic mutations? (Botkin, 1998). In doing this, it can be determined which embryos will be most likely to implant and germinate successfully in the uterus. PGD is a complicated, technologically sophisticated process. It is a union of in vetro fertilization technology and molecular biology (Botkin, 1998). Though it has numerous positive attributes, there are equally as many negative ones. In fact, this issue is one that has recently become the subject of many heated debates. Proponents for the use of PGD assert that this test allows for parents with fertility problems to maximize their opportunity for conception and birth. Their adversaries argue that this process is morally questionable, and though it is seen as safe alternative to abortion couples can experience the same psychological effects as if they were dealing with an actual abortion (Botkin, 1998). Obviously, this is an issue that does not have one distinct answer. Each opposing side has raised some poignant arguments. Those who are in favor of PGD generally use the arguments that it allows for the transmission of human genetic diseases to be reduced (McClure and Tasca, 1998). Before the usage of PGD the only other way to determine the existence of genetic diseases was by the use of prenatal diagnosis in the form of amniocentesis or chronic villus sampling (CVS). Currently, CVS can only be performed in the ninth to eleventh week of pregnancy, and amniocentesis can be performed in fifteenth to eighteenth week (McClure and Tasca, 1998). At this point, the fetus is developing within the uterus. Discovery of any abnormalities would pose the parents of the fetus with a difficult decision. They either continue a pregnancy that will result in a genetically defected child or abort the fetus. This is where PGD allows for what some would say an easier option. Because PGD is a pre- pregnancy test, abnormalities can be detected prior to the embryo ever being inserted into the mother. Currently, there are several diseases that PGD can detect such as Cystic Fibrosis, Tay-Sachs disease, Duchenne Muscular Dystrophy, Fragile X Syndrome, and Down Syndrome (McClure and Tasca, 1998). These are only a few of the diseases that can be detected but as the knowledge concerning human DNA increases there will be more detectable diseases. In addition to disease detection, PGD can also detect the gender of an embryo which can enable the determination of the existence of sex-linked disease or a sex chromosome imbalance (McClure and Tasca, 1998). Another of PGD's benefits is its ability to assist women over the age of thirty-five to successfully conceive. From this age group 50 percent of the embryos are chromosomally abnormal (McClure and Tasca, 1998). For these women, PGD drastically increases the odds for a successful pregnancy while the odds for miscarriage are reduced (McClure and Tasca, 1998). PGD also has promising outlook in cancer research. In the same manner that PGD detects single gene defects in embryo tests, it could do the same for polygenic diseases such as cancer (Yates, 1996). Experiments with genetic screening have been done concerning Tay-Sachs disease .The outcome of this research indicated that PGD has the potential to be extremely beneficial. Tay-Sachs disease affects 1 in 3600 Ashkensasi Jews, couples who were at risk for transmission of this disease to their offspring were genetically screened ( Robbers, 1990) . As a result of the screening, the number of children who were born with Tay-Sachs disease dropped from 50 in 100 in 1970 to 13 in 100 in 1980 ( Roberts, 1990). Due to the positive results from genetic screening, it is becoming somewhat more popular and accepted. In a survey done by Johns Hopkins School of Public Health, a group of people were surveyed to determine their likelihood to undergo genetic screening given their family history concerning colon cancer (Henderson, 1999). Those who had a significant family history of colon cancer as well as those who did not were eager to undergo gene testing (Henderson, 1999). At this point, genetic screening has begun with a good track record. Most of those who have used it or heard about it