Feb 6, 2019 in Informative

Genetic Testing

Introduction

Genetic testing or DNA diagnosis is a method that is based on modern, sometimes very complex technology, which can detect any genetic data (genetic information), damage of the DNA molecules that lead to severe and incurable diseases. Genetic testing is a search for mutations that cause various diseases. Some tests can detect changes in the gene; the others can detect changes in the protein which is encoded by the modified gene. One gene may undergo up to 300 mutations. Some of these mutations entail severe symptoms or death. The first genetic testing person goes back in the hospital. It is the test for phenylketonuria. Without special treatment the child is doomed to be a moron. The test allows prescribing treatment in time and avoiding severe consequences. Many of the healthy people can be carriers of genes of inherited diseases. It is so-called recessive genes. However, it happens that both parents are carriers of the recessive gene, and then the baby will be born with two "sick" genes. In such case the disease is imminent. Genetic tests allow parents to know if they can pass the genes of inherited diseases to their children in future. “Genetic testing is now available for an aver expanding list of genetic mutations associated with disease – including breast cancer, Parkinson’s and Alzheimer’s – as well as traits such as ancestry, intelligence, and athleticism.” (Soo-Jin Lee, p.77) Genetic testing is quite promising in diagnosis melanoma. According to Aspinwall: “The availability of predictive genetic tests for hereditary melanoma offers the prospect of tailored medical treatment and behavioral management recommendations to decrease impact and/or increase life expectancy among people at familiar risk.” The purpose of genetic testing or screening is to identify the risk of the disease before symptoms appear. This makes it possible, in some cases, to make treatment in time and in others – recommend measures to avoid transmitting a genetic disease to children.

Today, a wide range of genetic tests, and the possibility of genetic testing makes sweeping changes in the approaches to the diagnosis, prevention and treatment of many human diseases. However, the medical use of genetic testing raises a number of ethical, legal and social issues that require consideration and approaches to their solution to get the most out of new methods in health care.

Genetic information – is the data about heritable characteristics of individuals obtained by analysis of nucleic acids or other scientific analysis, which are the part of health information. (NHMRC) However, currently, the society has a view that the genetic information is different from any other medical information. This representation owes to several factors. These are historical reasons, the use of genetic tests, mainly for the purpose of diagnosis and prevention of rare monogenic diseases, which allows identifying particularly sensitive information about the relatives of the patient, the absence of most treatments of these diseases, the potential loss of control of samples of biological material, etc.

Ethical issues that arise in the use of genetic tests, mostly related to issues of personal use of the genetic information having a great psychological and social significance. Genetic data have a special status for the following reasons. They allow predicting the future state of human health with a fairly high probability and therefore genetic data can be used to infringe his/her rights as grounds for discrimination in the use of third parties. Genetic data can have a significant impact on the family for several generations, including descendants of the patient (Akinwounmi ).This paper will discuss the main questions as the ethical issues of genetic testing, the methods of genetic testing, advantages and disadvantages of genetic testing, etc.

Ethical Issues of Genetic Testing

Human genetic data can be collected, processed, stored and used for the following purposes: 

  • For the diagnosis and the provision of health care, including screening and predictive testing.
  • For medical, epidemiological and other scientific studies, genetic studies, as well as anthropological and archaeological research.
  • In forensic medicine in terms of criminal cases; etc (Rowley). 

Genetic testing is an integral part of the medical services for the population. It should not be imposed, but should be a matter of free personal choice. Full information about the availability of genetic tests should be freely distributed to a wide range of known and trusted sources, including public authorities, doctors and community groups of patients. “Serious ethical questions surround both genetic testing of individuals and genetic screening of population” (Tong).

The main justification for the use of genetic tests in the practice of health care is their medical benefit to the patient. In this regard, there are ethical problems when using genetic tests for inherited diseases with late time of onset for which there are no effective treatments (especially when testing children and adolescents), and genetic predisposition to widespread disease.

Pre-symptomatic testing for diseases with late time of onset should be available to adults, even in the absence of treatment, after appropriate counseling and informed consent. In terms of pre-symptomatic testing of adults for incurable disease, the following conditions should be kept: information obtained will be used for the prevention of harm to the patient, his family, future children, etc.; the patient is fully informed about the limitations of the test, including the possibility of non-informative results and the inability to predict the time of onset and severity of symptoms; the patient is able to perceive the information and give consent on its basis; there is a program of counseling and psychological support for the tested people.

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Genetic testing of non-adult or incapable for purposes of diagnosis or medical care is considered ethically acceptable only if the obvious medical benefit is directly for the tested person. According to Borry: “The companies that allow genetic testing of minors underline that decisions about genetic testing of minors belong to the realm of parental discretion.” In the absence of medical benefits for children and adolescents (lack of prevention and treatment), it is recommended to postpone pre-symptomatic testing until adulthood, when young people can make their own decisions. If it is necessary to test children for making reproductive decisions by another member of the family, it is recommended to use test results of the child by a doctor in order to calculate the risk for the relatives, but not report it to their family. It is also recommended to postpone the notification of the results until the adulthood of the child, if he or she wants to use this information.

The main purpose of genetic testing in common diseases – is the evaluation of the risk of disease and identification of individual measures for its prevention in high-risk individuals. Basic restrictions of applying such tests are associated with insufficient knowledge about the number of genes involved in the process, how they are combined, interact and what influence have the environmental factors on the genes. Further study of genes has undoubted scientific value, but most researchers tend to believe that these tests do not provide enough information for the practice of medicine. 

Methods of Genetic Testing

There are different methods of genetic testing that are used for clinical purposes. Genetic testing – is an analysis of human DNA, RNA, chromosomes, proteins, ferments of metabolites. It is used to identify carriers of recessive alleles of genes that cause hereditary diseases. (Paralkar)It is also used to predict the risk of disease, for prenatal diagnosis or prognosis of disease, prenatal screening, and screening of carriers and babies. Thus, there are the following methods of genetic testing:

  • Genetic tests (examines individual genes or relatively short sections of DNA or RNA).
  • Chromosomal tests (examines targets chromosomes or very long DNA segments).
  • Biochemical tests (examines the level of a certain protein or enzyme).

Methods of gene or DNA testing are particularly promising, which directly examine the DNA molecule. They are based on nanotechnology and the use of advanced computer, information and biotechnology with using automated systems and robotics laboratory. For genetic testing, DNA probes are used, which are placed on special matrices (gene chips or DNA chips) with the size of a fingernail or a microscope slide. Then the analyzed genetic material is putting. After joining the complementary sites of DNA probes, the data are analyzed, for example, for the presence or absence of mutations of studied genes. Various modifications of these methods are used not only in the clinic but also for research (search for genes, determining of DNA sequences, gene expression, scanning and screening of mutations and so on.), which in its turn contributes to the development of new diagnostic tests.

Genetic tests are effectively used in clinical practice. However, the cost of DNA testing conducted in clinical laboratories is quite high and, depending on the size of the studied genes, the number of mutations under test and other factors can vary from hundreds to thousands of dollars. 

“Chromosomes are not visible in the cell’s nucleus—not even under a microscope—when the cell is not dividing.” (Genetics Home Reference) They are the large DNA-containing structures in the cell nucleus. Usually, people have 23 pairs of chromosomes: 22 pairs of autosomes (1 to 22) and 1 pair of sex chromosomes (XX in females and XY in males). Chromosomal testing studies the features of human chromosomes, including their structure, number and location. This test makes it possible to identify such changes as the removal (deletion) of chromosomes, expansion or modification of the normal location of chromosome (translocation).

Biochemical tests make it possible to determine the level and activity of the major proteins. As long as genes contain DNA code, which is required for the formation of proteins, the number of abnormal proteins or their impaired activity may indicate certain genes that are not functioning normally. 

Such tests are often used in screening of newborns. For example, biochemical screening can help identify children with metabolic disorders such as phenylketonuria. Due to the genetic defect in patients with phenylketonuria, the ferment that breaks down the amino acid (a structural component of protein) phenylalanine is missed. As a result, phenylalanine builds up in the body, its level becomes much higher than normal, and this leads to various health problems.

If phenylketonuria is diagnosed at an early stage, in this case, the disorder can be kept under control with a strict diet low in phenylalanine, avoiding high-protein foods and those foods containing certain artificial sweeteners.

Advantages and Disadvantages of Genetic Testing

The decision to conduct genetic testing can be quite difficult. The person chooses to be tested or not. Therefore it is important to discuss and understand all the information that was provided to the person in order to help make a right decision. It is also important to have the opportunity to discuss with the doctor any questions or concerns that everyone may have.

Genetic testing can be very useful, but there are also a significant number of risks and constraints. It is necessary to understand the benefits and risks of testing before making a decision. Some of these benefits and risks are discussed below. 

Advantages

Genetic testing is able to tell the exact information about the genetic features of the person and his/her child. For some people such resolution of uncertainty is very important, even if the received news is bad. If the news is good, it can bring the great relief.

“Medical benefits include the possibility of preventive or therapeutic interventions, decisions about surveillance, the clarification of diagnosis and prognosis, and recurrence risks.” (Ross) Genetic testing can help establish the diagnosis of hereditary diseases. If a person has an accurate diagnosis, the appropriate treatment can be offered. If the results of genetic testing show that the person has an increased risk of any disease in his/her lifetime (for example, breast cancer), he or she may be offered a program of regular surveys to minimize this risk.

The results of genetic testing may provide useful information for planning future child. If it is known that the person or her partner are at high risk of having a child with a genetic disease, it is possible to conduct testing of unborn child during pregnancy (prenatal diagnosis) to find out if he/she is sick. “In the case of carrier and prenatal genetic testing, a positive test result raises reproductive options, including abortions that are so abhorrent to some people that they would prefer to remain ignorant to the risk.” (Holtzman) The information that the person has an increased risk of having a child with a genetic disease, can allow being better prepared mentally and practically.

Since hereditary diseases are often transferred within the family, information about person’s genetic features may be useful to other members of the family. If the relatives are aware that the hereditary disease is transferred in family, it can help to avoid misdiagnosis and time loss. This information may also be useful when planning their child.

Possible risks and limitations

Conducting genetic testing, waiting for the results, and, then, receiving it can cause a wide range of emotions, such as relief, fear, anxiety or guilt. It is important to try to take both good and bad news in the context of the possible consequences for the person and his/her family. “The risks of genetic testing include the inability of such testing to detect all mutations, the unclear efficacy of some interventions, and the possibility of psychosocial or financial harm.” (Howard-McNatt)

Even if a genetic test is able to confirm the diagnosis, it may be so that there is no route of exposure or treatment for this particular disease.

In some people, the genetic or chromosomal changes (mutations) are not detected. This does not necessarily mean that the mutations are absent. Some genetic changes are extremely difficult to detect by modern laboratory methods. In such cases, attempts to clarify the diagnosis can be very disappointing. 

Genetic mutations are often transferred from generation to generation. Thus, the results of the person’s genetic test can make the obvious genetic information of other family members, especially their own risk of having a hereditary disease. Will anyone of the family members want to know about it?

It may be important to understand how the results of genetic research may affect person’s insurance or professional employment before delving examination.

The testing results can sometimes reveal family secrets, including the issues of paternity and adoption. Having done genetic testing once and having gotten the results, they cannot be changed.

Conclusion

Pre-symptomatic diagnosis is essentially a new possibility that allows in some cases to implement effective preventive treatment, and starting appropriate preventive measures. However, even in cases when there is no effective treatment for the disease, the receiving of information about the presence or absence of abnormal gene for families with cases of hereditary diseases is of great moral and psychological value and serves as the most important factor for making many vital decisions associated with family planning and procreation, choice of work, etc.

Approximately 4% of all cancer is caused by heredity. (WHO) Genetic testing can assess the risk of disease by analyzing the genetic mutations responsible for this risk. The results will help to make an informed decision on prevention and reducing risk in the early diagnosis of cancer. Even if the patient has been found to have cancer, genetic method will provide the doctor with necessary information about the risk of developing the second cancer that will help choose the most effective treatment strategy.

Genetic diagnosis provides important information for relatives. In case of detection of gene mutation increases the risk that parents, brothers, sisters, children can also carry these mutations. Pre-symptomatic diagnosis of family members will provide a real opportunity to prevent disease. The greatest contribution of genetics in health care consists in the fact that it allows to modulate the risk of disease. 

It should be noted that the predictive medicine is the medicine based on clinical understanding of the functions of the genome, its components – genetic groups and individual genes, only is taking its first steps. With the identification of new genes, the elucidation of their functions, new data on metabolic ways, information on the molecular mechanisms underlying certain morphogenetic processes, as well as certain diseases, especially multifactorial, the role of predictive medicine in health care will grow.

Despite the challenges that exist in the field of genetic testing, it is developing rapidly. According to Hanoch: “DNA technology has been developing rapidly, leading to an enhanced use of genetic testing in our understanding of disease diagnosis, treatment, and prevention.” The application of genomic technologies in the diagnosis of disease, the creation of genetic databases, the development of bioinformatics, robotics - all this will assist to more accurate prediction of disease development, the use of more effective treatments and targeted prevention. “Current practices of proprietary databases may hinder interpretation of genomic data and impede the advance of personalized medicine.” (Cook-Deegan) The combination of large-scale application of genetic diagnostics, including analysis of gene expression, and methods of pharmacogenomics will allow identifying the genetically determined features of metabolism of drugs in patients and then using specially developed drugs, recommending appropriate lifestyle that will significantly increase the effectiveness of drug therapy and reduce the risk of adverse reactions.

It is also important to pay attention to the existing gap between the real possibilities of genetic testing as a complex of molecular techniques and a clear disadvantage of thoughtful clinical guidelines that must complete each genetic testing. Extensive involvement (in the solution of these issues) of experts in medical genetics competent in the clinical examination and therapy, as well as physicians of relevant profile (cardiologists, oncologists, obstetricians, and others.), with the basics of preventive (predictive) medicine, currently, are particularly relevant.

Moreover, it should be emphasized that any genetic testing as part of predictive medicine is justified only if its results are backed by serious medical advice. Genetic testing that is not backed with qualified medical and genetic counseling and, if necessary, with the recommendations of the experts, is meaningless and, by and large, can only be harmful.

Understanding of the functioning of genes in normal and pathological conditions in the development or aging of the organism, the development of malignant tumors, when exposed to various environmental factors will control the development of widespread multifactorial diseases. The practical significance of genetic testing will increase if and effective methods of gene therapy are developed.

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