Molecular Genetic Diagnostics in the 21st Century - Term Paper Example

Molecular Genetic Diagnostics in the 21st century: The advent of molecular genetic diagnostics has opened up new opportunities in the field of preventative and restorative healthcare. The newly available genetic diagnostic technologies have given rise to legal and moral conundrums that have not been sufficiently resolved. Just as the debate on the broader implications of genetic technology continues, the number of patients willing to avail of the technology is also on the rise. Such trends are witnessed here in the United Kingdom, as elsewhere in the industrialized world. This essay will discuss the molecular genetic diagnostic techniques that are currently being employed for various medical conditions. Even as the civil society waits to take full advantage of this quantum leap in medical science, a few scientific, ethical and practical issues remain unaddressed yet. New genetic technologies promise to radically alter the conventional methods of medical diagnostics. For constituents of the healthcare industry they offer a commercial opportunity. The progress that we are witnessing in genetic diagnostics presage a revolution in the way health care industry is organized. For example, the existing technology allows practitioners to ascertain a patient’s vulnerability to certain hereditary conditions. Quite soon, diagnostic techniques will advance to a level where genetic tests will indicate who will respond well to a drug, who will respond poorly, and who will suffer adverse reactions. Researchers at Bristol-Myers Squibb, for instance, “have shown that different individuals have different degrees of responsiveness to the cholesterol-lowering drug Pravachol, depending on which of two variants of a polymorphism encodes the cholesterol ester-transfer protein (CETP)” (Petersen & Bunton, 2002). In a few other cases, the central issue isnt the level of patient responsiveness but the risk of a negative reaction to the drug. To cite a recent example, patients, whose carry mutations in the CYP3A family of cytochrome P450 enzymes, can have fatal cardiac reactions to the antihistamine Seldane if they are also taking the antibiotic erythromycin. Such discoveries about the dynamic processes of molecular genetics can help Doctors to tailor their prognosis to the needs of the particular patient (Petersen & Bunton, 2002). Genetic diagnostics can help increase the efficacy of prescribed drugs by identifying which class of drug would be most effective for specific groups of patients. For example, “Hypertension can be treated with angiotensin-converting enzyme (ACE) inhibitors and beta-blockers, as well as with calcium channel blockers. But not all patients respond to these medications in the same way: many doctors now tend to prescribe ACE inhibitors and beta-blockers to African-Americans, for instance, because these drugs seem to work more effectively on them. An unidentified genetic trait probably explains such differences, but without proof, physicians must arrive at a course of drug treatment by trial and error. Genetic Diagnostics might provide scientific confirmation, thereby organizing and accelerating the process of matching drugs for all sorts of diseases with appropriate patients or groups of patients” (Rados, 2005). Genetic Diagnostics is a valuable tool in treating more serious medical conditions like cancer, cardiovascular ailments and diabetes, which require a long-term treatment approach. In conventional medical practice, the physician will be able to determine the suitability of a particular course of chemotherapy only after a few weeks into the course. By predicting the right category of drug for the patient, genetic diagnostic techniques can help minimize risk to the patient. Rheumatoid arthritis is another area, where researchers have recently discovered that patients with certain genetic predispositions “responded positively to a single class of drug than to a highly toxic combination of three classes, the more frequently prescribed therapy” (Rados, 2005). Yet, we are still only in the initial stages of developing fool proof techniques of genetic diagnostics. In the year 2001 alone, 180,000 women across the world were diagnosed with breast cancer; and the number has steadily grown in the years since. Like other life threatening diseases, the successful treatment for each of these women will depend on many factors, the foremost among them being the timing of the diagnosis. Diagnosed early, most types of cancer can be contained and eventually cured. It is in this context that genetic analysis comes in handy to expedite diagnostics. Some of the most advanced techniques for detecting cancers-- including lymphoma and leukemia--are based on genetic diagnostics. While CAT scans still have their utility as a diagnostic tool, they are now supported by biopsy analysis techniques that use gene probes to detect in cells cancer-inducing genetic mutations. In particular, “cellular DNA may be fragmented, tagged with a fluorescent marker, and checked for its binding pattern with microarrays of DNA sequences on glass chips. In addition, the genetic abnormalities associated with various leukemias and lymphomas can be rapidly detected with the aid of the so- called B/T gene rearrangement test. The test is based on the recognition that most leukemias and lymphomas are characterized by genetic rearrangements in the B and T cells of the bloodstream. A study conducted at the University of Ulm in Germany revealed a correlation between various chromosomal abnormalities and the length of survival of leukemia patients. Analysis of the rearrangements has permitted patients to benefit from more expeditious and accurate diagnoses that, in turn, have led to more appropriate treatments” (Bhandari et. al., 1999). The technology to pre-determining the gender of a developing fetus is a recent development in medical science. The two most prevalent techniques used are sperm sorting and genetic testing. The techniques work on the principle that a random sample of sperm will contain an equal mix of male and female chromosomes, “although girl-making sperm are heavier and slower, due to carrying more DNA, than their male counterparts” (Bhandari et. al., 1999). Nevertheless, they can be separated and marked with a fluorescent marker in the flow cytometer machine. Presently, this molecular genetic technique is only offered in the United States. The other technique employs a centrifuge to segregate X and Y chromosomes. After this, the sperm can be used for In-Vitro-Fertilization or intrauterine insemination procedures. The government is yet to draft comprehensive regulations to monitor their use. Moreover, the success rates so far have not been outstanding. A technique that has found greater success is called pre-implantation genetic diagnostics (PGD) (Silverman, 2005). After an egg is fertilized through IVF or Intracytoplasmic Sperm Injection (ICSI), a cell is sampled from the embryo to test for diseases as well as to determine the sex of the developing embryo. Conditions such as cystic fibrosis, Huntington’s disease, Haemophilia and Down’s syndrome could all be detected at this early stage, so that the parents can choose between continuing the pregnancy and aborting it. Although this technology was intended to prevent the birth of defective children, it has been used by some clinics as a sex-selection offer, which raises many unaddressed questions of ethics and morality (Silverman, 2005). In the United States, due to the improvements in genetic diagnostic devices and the assurance from the Food and Drug Administration, doctors are starting to gain insights into how certain diseases pass from one generation to the next. The Tag-It Cystic Fibrosis Kit is one such device. Cleared for marketing in May 2005, “Tag-It finds genetic variations in what scientists now know is the gene that causes cystic fibrosis--the most common fatal genetic disease in the United States. Made by Tm Bioscience Corp. of Toronto, Tag-It will help diagnose cystic fibrosis in children and identify adults who are carriers of the gene” (Silverstein, 2001). Moreover, with the human genome project having been completed, it provides physicians with a comprehensive source of information about the “structure, organization, and function of the entire set of human genes--all 30,000 to 40,000 of them--and an idea which ones affect health and disease” (Silverstein, 2001). This genetic database, alongside another research tool called a microarray, gives a brief overview of genes that are active in both normal and diseased cells. A microarray, also referred to as a gene chip, “is a tiny glass or plastic platform containing thousands of genes. It is similar to a computer microchip, but instead of tiny circuits, the chip contains "probes" or genes with a known identity, such as DNA or small pieces of DNA, which are arranged in a grid pattern on the chip. Whenever genetic material from a patients blood or other tissue is placed on the chip, the probes react. Those reactions can be detected and used to screen for the presence of particular genetic sequences, such as those related to diseases, and how people will respond to certain medications. Microarrays also can enable researchers to see which genes are being switched on and off under different medical conditions” (Breheny, 2007). Such devices are tailored to different branches of medical science as well, spawning in the process, new fields of specialization such as pharmacogenomics, metabolomics (the study of body fluids to determine changes in metabolism) and proteomics. But there is still plenty of research to be done and the task of developing efficacious medications and precision diagnostic devices continues to be extremely complex and cumbersome (Breheny, 2007). The small successes provided by molecular genetic diagnostics augur well for the future of medical science. In the future, genomic testing devices will further add to the repertoire of already existing genetic diagnostic devices. For example, Genomic tests may help study the activity of many or all genes simultaneously, while genetic tests, a subset of genomic tests, will help identify abnormalities in a patient’s genetic code. A breast cancer microarray chip that identifies the particular genes among the group of 70 genes can be taken as the template for genomic testing device. Also, OF QF-PCR is a new procedure that is well suited to the rapid detection of aneuploidites in antenatal amaiocentesis or chorion villus samples and is already being used in some clinics. The Multiplex litigation-dependent probe amplification technique is ideally suited to dosage testing of multiexon genes (Johns, 2001). A key area where genetic and genomic diagnostic devices might find application is in treating HIV infections. Due to the rapid evolutionary nature of these viruses, drugs are presently constantly being made obsolete. Similarly, some drugs require the digestive system to metabolize them at just the right rate--neither too soon nor too slowly –in order for it to induce desired outcomes. Genomics are already being used to tackle these two problems, as the following examples illustrate: “The TRUGENE HIV-1 Genotyping Test, made by Visible Genetics Inc. of Toronto and cleared by the FDA in 2002, is a genetic test that allows doctors to determine from a blood sample whether a patient carries drug-resistant strains of HIV-1. If so, the patient can be given a different drug. The AmpliChip Cytochrome P450 Genotyping Test, made by Roche Molecular Diagnostics, is the first genetic lab test cleared by the FDA that uses DNA extracted from a patients blood to detect variations in a gene that affects how certain drugs, such as antidepressants, anti-psychotics, and some chemotherapy medications, are broken down and cleared from the body. Doctors can then adjust a drugs dosage for an individual patient” (Johns, 2001). These new developments in genetics and genomics are altering the way in the legal system as well. The invention of DNA identifying techniques has already made forensic analysis a more reliable enterprise. Juries, who previously depended on circumstantial evidence for arriving at their verdicts, now peruse forensic analysis for more direct proof. Genetic diagnostics has found application in cases of family law as well, including here in the UK. Since the dawn of time, men have worried whether their child is really biologically related to them, a fear that has noted in human mythologies and more recent literary works. To further fuel this fear, a recent study has indicated that one in seven men are not the biological fathers of their children. These days, using genetic technology, fathers can allay these fears through the help of a simple test; and can rest assured that they are indeed the father of their child in the basic sense of the word. References: 10 Medical Breakthroughs to Watch for in the Next 10 Years. (2006, March 29). Daily Herald (Arlington Heights, IL), p. 1. 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