Genetic Testing: Future Direction and Synopsis
Matt Talbert
Future direction of Genetic Testing |
Future Directions of Genetic Testing
New Test Methods: Conversion, DNA Chips
Technical Problems with Genetic Testing
As biotechnology advances, several new basic laboratory techniques, built upon our more recently acquired knowledge of genetics, will be applied to genetic testing. This will enable more sophisticated and efficient detection of DNA abnormalities.
Conversion:
One example of a new laboratory method that has recently been developed, able to aid in the detection of almost any kind of mutation by reducing the complexity of genetic material to be analyzed, is known as “Conversion.” In this method, cells from a patient are combined with cultured rodent cells, creating a hybrid cell that has only a single set of human chromosomes. The diploid nature of the human genome (meaning that we have two of each chromosome) can sometimes complicate genetic testing, especially in cases of heterozygosity, when someone has one mutant allele and one normal allele. Therefore, the single chromosome of interest that contains the mutant allele can be extracted from the hybrid cells and be more clearly studied. From this method, scientists can expect much improved test sensitivity through either the use of conversion itself or the use of the concept behind conversion in accordance with already established procedure (Yan et al., 2004).
Additional Comprehensive DNA Chips:
Another example of a developing genetic testing technology is the DNA Chip. The DNA chip in principle is simply a modified DNA microarray, a glass slide onto which oligonucleotides complimentary to disease mutations have been dotted in a pre-determined grid format. Something similar to this was already discussed regarding breast cancer but enough knowledge has been uncovered regarding many other kinds of genetic diseases to further implement the idea. A disease such as cystic fibrosis may be caused by hundreds of different kinds of mutations in the gene that is under scrutiny. Just because one particular mutation is the most common cause of cystic fibrosis does not mean that this will be the cause in all people. A DNA chip would take all possible mutations of the cystic fibrosis gene into account and enable scientists to perform one test, from derived RNA or complimentary DNA, to detect any possible mutations in the cystic fibrosis gene. This technology would greatly improve the accuracy of genetic testing, resulting in far less false negative test results (“Gene chip technology…”, 2004).
Scientists recently gathered to debate the need and their recommendations regarding the possible extension of genetic testing beyond individualized healthcare and to being a part of public health. In the future, society will likely see more genetic screens conducted for the purpose of early identification of genetic disease. These population tests will likely be selectively offered to high-risk ethnic groups or families with documented genetic illness rather than the entire populace. However, certain tests will likely be more commonly offered than others depending on the incidence of the disease in question. Scientists stress that though public knowledge of genetic status would seem to be an obvious benefit, most people would require professional guidance in order to correctly interpret a positive or negative result (Godard et al., 2003).
Additionally, as was mentioned earlier, testing of approximately twenty different genes related to the way that the body processes certain types of food as well as certain kinds of ancestry testing, are available in commercial malls in Los Angeles. The public will likely undergo more minor forms of genetic testing to satisfy a desire for knowledge or for leverage in their personal life. Leverage in one’s personal life might mean, among other possibilities, that a nutritional profile indicating a reduction in the ability to break down cholesterol may motivate someone to reduce fried food intake. If the social mechanics of the United States follows previous patterns, something that is trendy in one place will soon spread to the entire nation. Therefore, it should not be surprising to see a dramatic increase in the voluntary public use of genetic testing in some scenarios as it becomes more “contemporary” (Fogarty, 2004).
The concept of a DNA data bank has been one that has long existed and been successfully implemented in the case of forensics databases. A DNA data bank refers to a storage facility that would keep a running catalogue of genetic material for future DNA extraction and analysis. Forensics databases have used genetic testing technology in order to match DNA from crime scenes with the genetic profiles of on-file convicted felons. These profiles match archived DNA with suspects by matching polymorphism profiles, unique individual variation in the genetic code. The concept will likely be expanded to research purposes, for instance, a particular genetic abnormality could be archived with the permission of the patient it was extracted from for other laboratories to use in research at will. This shared access to particular genetic variants would make public sector disease research both more accurate and efficient (McGrath, 2002).
Current regulation of genetic testing is implemented by the Clinical Laboratory Improvement Amendments (CLIA) or an assortment of other federal organizations depending on the kind of test. If a genetic test is offered as a kit, a product that can be sold to clinics after manufacturing in a biotech facility, the FDA has full jurisdiction. Under this jurisdiction, IRB and FDA approval are required. The acquisition of FDA/IRB approval involves undergoing experimental trials that test the validity, accuracy, and applicability of a genetic test before it can proceed to market. However, a genetic test offered as a laboratory service must simply meet certain CLIA certifications and be experimentally accurate as a technique (Holtzman et al., 1997). In the future, scientists are concerned that private business might prey on the public through common misconceptions, such as the idea that a genetic test can define precise disease risk. Therefore, it can be anticipated that the FDA and other government agencies will attempt to expand their jurisdiction to all types of genetic testing for the good of public protection (Holtzman, 1999).
Though genetic testing is an extremely powerful and valuable tool, there are certain limitations to what it can tell us:
Public/Professional Education-
As indicated by the recent breast cancer study results involving public screening and direct to consumer advertising of the BRCA1 gene test, neither the patients nor healthcare professionals were able to correctly interpret the complexities of test results (U.S. Government, 2004). Additionally, the advertising often encouraged the participation of women that didn’t necessarily need the testing done, women being tested solely on the basis of a few sporadic cases of breast cancer in their family (“Genetic Testing Meets Mad Ave,” 2004). Though cases of breast cancer in the family are certainly danger signals, it only applies to women with a certain number of familial “risk factors” determined by how many and which relatives have breast cancer (Ponder, 1997). The points brought up by the BRCA1 campaign certainly indicate that a great need for public education is present. Most scientists suggest that public education about genetic testing should come from newly trained physicians or genetic counselors (“Genetic Testing Meets Mad Ave,” 2004).
However, due to the fast-paced world of American medicine, physicians are likely unable to be educated to the degree that they should in order to accurately recommend or interpret genetic testing. Genetic counselors are also somewhat of a dead end possibility, as there is presently a severe shortage of both existing counselors and those currently in training (“Genetic testing to expand . . . ,” 2004). Dramatic changes to medical education and increased recruitment of genetic counselors is likely to occur in order to remedy these concerns.
Figure 17) Genetic counseling is a relatively new field where trained professionals advise patients on an individual basis of how to interpret a particular test result and its implications for the future (Genetic Counseling, 2004).
Genetic testing is one of the most powerful tools that humanity possesses in the pursuit of bodily perfection. The foundations of classical laboratory techniques, such as dot blotting, and the innovation of new techniques, such as conversion, have enabled us to discern the otherwise intangible direct qualities of our biological inheritance (Yan et al., 2003). Among science’s current genetic testing abilities include the capacity to determine carrier status, diagnose disease, predict disease risk, select for healthy children in reproductive clinic and monitor the genetic health of newborns. These abilities have evolved our scientific understanding to a precipice overlooking an even greater depth of enigma; for all our advances, we have barely scratched the surface.
Though we can predict and diagnose illness as a consequence of our genetic inheritance, most of the treatment options that medicine possesses fall into the domain of prophylactics or selection against affected children (Godard et al., 2003). Additionally, there are certain limitations to our current understanding of genetic illness such as our inability to assess precise risk from a test result or our inability to differentiate genetic influence from environmental influence (“Pros and Cons,” 2003).
In the future, we can expect to see genetic testing encompass more advanced laboratory methods (Yan et al., 1994) and a possible public health role (Godard et al., 2003). We can also anticipate the creation of more convenient scientific databanks through archival of DNA samples (McGrath) and more stringent regulation by various governmental agencies in light of recent misinformed public response (Holtzman, 1999). Regardless of the particular advances that occur, there can be no doubt that genetic testing will see both scientific advancement and greater incorporation into primary healthcare (“Genetic testing to expand, but staffing shortage looms, 2004).
Questions or Comments: Email Dr. Verna Case
Davidson College Biology Department
Davidson College
This web page was produced as an assignment for an undergraduate course at Davidson College.
Future direction of Genetic Testing |