The Genetic Screening Debate

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The Genetic Screening Debate Within the past thirty years, researchers have found strong evidence linking genes and disease. The development of predictive genetic tests followed shortly after the isolation of certain candidate genes. Although predictive genetic screening is only available for a handful of diseases, its effects and ramifications have become hotly debated issues in a wide range of areas, from government to religion. The debate began in the 1993 when researchers isolated the BRCA1 gene, which is associated with increased risk of developing breast and ovarian cancer. The discovery of this gene led to excitement and speculation of developing a predictive genetic test to identify those women at risk for these cancers. In this paper, I will first describe the biology of genetic testing, and then discuss the pros and cons of predictive genetic testing. Before we start discussing how genetic tests are developed, let us discuss how genes can trigger disease. A sound body requires the action of many proteins working together. For a protein to function properly, an intact gene must encode for that specific protein. A mutation describes a gene which has been changed. The most common type of mutation is a single change of a nucleotide of DNA. Other types of mutations include the loss or gain of a nucleotide and the disappearance or multiplication of long segments of DNA. Mutations can have three effects: beneficial, harmful, or neutral. Mutations are beneficial if the fitness of an individual is enhanced. Harmful mutations can either slightly alter a protein, where the protein may still minimally function, or they may totally disable a protein. In this instance, the outcome is not only based on how a mutation alters a protein’s function, but on how important the protein is to the body (Understanding Gene Testing). Since we have determined how genes can trigger harmful effects in the body, we can now examine how scientists look for specific genes that cause diseases. Scientists, looking for a diseased gene, study DNA samples in individuals where the disease has been present in the family for many generations. They look for specific genetic markers, which are DNA segments that are identified in individuals with the disease, and not identified in healthy individuals. Scientists then narrow down the area of DNA by mapping a gene. If a disease gene is mapped to an area, then the genelike sequences become candidate genes for a specific disease gene.

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