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Genetic Testing

I. What is Genetic Testing?

The analysis of human DNA, RNA, chromosomes, proteins and certain metabolites in order to detect heritable disease-related genotypes, mutations, phenotypes, or karyotypes for clinical purposes. Such purposes include predicting risk of disease , identifying carriers, establishing prenatal and clinical diagnosis or prognosis, monitoring screening, prenatal and in newborns.

II. Types of Genetic Testing

III. Types of diseases found from Genetic Testing

IV. Why Get Tested

V. Legal and Ethical Issues

VI. Case Studies  


Suppose you are at risk of a genetic disease that threatens to render you unrecognizable to yourself. Physically you realize the disease will slowly erode your body to an incontinent mass of uncontrollable jerks and twitches. Mentally, it will eat away at your brain cells impeding your ability to remember, pay attention, reason. And emotionally it will blacken your days with irritability and all consuming depression. Worst of all you know that the disease cannot be prevented or stalled, arrested or cured. To learn that you have the offending gene is to receive a virtual death sentence that leaves only two questions unanswered: when will the nightmare begin? And how long will the suffering last?

Do you really want to know if you have the disease? Are you sure you want to know now if the symptoms may not appear for decades? Are you prepared to handle the potential consequences of that knowledge? That is what genetic testing can tell us.

I. What is Genetic Testing?

It is the analysis of human DNA, RNA, chromosomes, proteins and certain metabolites in order to detect heritable disease-related genotypes, mutations, phenotypes, or karyotypes for clinical purposes. Such purposes include predicting risk of disease, identifying carriers, establishing prenatal and clinical diagnosis or prognosis, monitoring, screening, prenatal and in newborns. Genetic testing involves looking at different characteristics of an individual's DNA and comparing it to characteristics of DNA from those that have known genetic disorders. The DNA used for genetic tests is usually isolated from a sample of blood or other body fluids and tissues. The DNA is then subjected to different tests that will allow for different characteristics of the DNA to be observed and compared.

Genetic tests include techniques to examine genes or markers near the genes. Direct testing for diseases such as cystic fibrosis and sickle cell anemia come from analysis of an individual's specific genes. A technique called linkage analysis is used when the gene can not be directly identified but can be located within a specific region of a chromosome. Genetic testing is a complex process and the results depend both on reliable laboratory procedures and accurate interpretation of results. Tests also very in their ability to detect mutations or to detect all patients who have or will get the disease. The most common type of genetic testing performed today is the screening of newborns. IN the US 4 million newborn infants are tested for genetic abnormalities. Some tests look for abnormal addrangements of DNA, and others detect inborn errors of metabolism, such as phenylketonuria (PKU) by confirming the absence or presence of a particular protein involved in abnormal development.

II. Types of Genetic Testing.
Carrier Identification: This includes genetic tests used by couples whose families have a history of recessive genetic disorders and who are considering having children. Three common tests include those for cystic fibrosis, Tay-Sachs disease, and sickle cell.
Prenatal Diagnosis: This is testing of a fetus. This may occur when there is a risk of bearing a child with genes associated with mental retardation or physical deterioration. One of the most common diseases screened by this method is Down syndrome.

Newborn Screening: This is done as a preventative health measure. Tests usually have clear benefit to the newborn because treatment is available. Phenylketonuria and congenital hypothyroidism are conditions for which testing is conducted.

Late-onset Disorders: this includes diseases such as cancer and heart disease. These diseases are complex and have both genetic and environmental causes. Genetic tests may indicate a susceptibility or predisposition for these diseases. Huntington's Disease can also be tested by using this method.

Identification: this is basically DNA Fingerprinting. This is when you use genetic markers to identify unique characteristics of an individual. This kind of information is used in legal cases such as paternity and also in criminal investigations ( EG. OJ Simpson case).

III. Types of Diseases that are genetic and can be tested

There are over 4,000 diseases that are known to be genetic and are continuously passed on from generation to generations. Of course there are not that many diseases that can be tested with genetics, are few of the diseases that are tested with genetics are: Tay-Sachs Disease, Huntington's Diseases, Cystic fibrosis, Alzheimer's disease, colon cancer (familial adenomatous polyposis (FAP)), breast cancer (TP53, BRCA1 and BRCA2), Thyroid Cancer (RET), Sickle Cell Anemia, Down Syndrome, Phenylketonuria, Congenital hypothyroidism

IV. Why get tested?

A person may want to get tested if there is a family history of one specific disease, they show symptoms of a genetic disorder, or if they are concerned about passing on a genetic problem to their children. A lot of testing is done by couples who are thinking of having children and they want to know if they will pass any kind of disease on to them. (Read story somewhere in here)

V. Legal and Ethical Issues

There are a lot of concerns right now about genetic testing. Some of the legal issues that have been brought up are about insurance companies. If a person were to test positive for example with the gene for cancer and the insurance company finds out about this. The company could either deny the person coverage, drop them from their company or they could also raise the premiums that the person pays. Another fear is that if employers find out about the results of a genetic test they could choose to fire the person or not to hire them at all. There is also more recent concern about being admitted in to universities. The University could choose to not admit a person because why should they waste an education on someone who could inherit a life threatening disease when they can give that spot to a person who has no genetic disease. This brings up the ethical issue of being tested. How confidential are the results of one's test going to be. Should the physician have the right to tell the patients family. In the end the results are primarily between the patient and the physician but there is also chances that the other people have access to that information. (Read highlighted parts from Genetic Testing Law)

V Case Studies

Case 1

Frank Gold, a 23 year old man appeared at the Medical Records Department of a long -term care facility. This facility included skilled, intermediate, and long-term/custodial care as well as residential accommodations for the elderly. The young man asked for the medical records administrator for information about his maternal grandfather, who had lived at the facility for more than 20 years, when he was in his sixties and seventies, but had not died there. He had no information as to where or from what his grandfather had died and no on in his family would discuss the grandfather or what had happened to him. Mr. Gold was generally aware from his memory of his grandfather that he acted strangely , had a difficult time remembering things and near death did not even recognize his family members.

The young man was about to be married and was concerned about the mystery surrounding his grandfather's demise; he was especially interested in obtaining information relevant to genetic history, in view of his impending marriage. His mother had died of breast cancer three years previously at age 58, but Mr. Gold had been concerned that before her death she had begun to show early signs of premature senility. He had no idea whether her condition was related to his grandfather's but he was curious. He did not have any authorization form from his grandfather's next of kin ( Mr. Gold's Uncle) to obtain information from the patient record, as the knowledgeable family members had closed ranks and refused to discuss the grandfather. Sate law and institutional policy required a signed authorization form from the next of kin to release information from the medical record of a deceased patient. Should Mr. Gold to told?

Case 2

In an attempt to provide as much information as possible to clients needing to make decisions about their pregnancies, the OB/GYN department of Springfield Hospital determined that the cytogenetic technologists should assist in the counseling process. Counseling teams were established with each team consisting of a physician, nurse, member of the clergy, and the technologist. The role of the cytogenetic technologist was to provide date about chromosomal and biochemical abnormalities, statistical probabilities, and evaluation techniques.

James Morison was a cytogenetic tech who was joining such a counseling team. While coursed in counseling had been included in Mr. Morison's educational program, this assignment was the first real experience that he had in the counseling process. He is confronted almost immediately with the assessment of how to balance appropriately his role as a fact giver with his inclination to offer advice. It becomes clear that the facts are interpreted differently by each client and that he must assume more responsibility for interpretation of the information to the client.

When presented with information about the presence of an abnormality some clients immediately opt for abortion, regardless of the severity of the problem. Other women insist on carrying to term babies that will be seriously deformed with little hope of a normal life. The technologists must find some way of assisting these women in making informed decisions.

For example, Mr. Morison's first case involved a 35 year old married woman who was 18 weeks pregnant and had been diagnosed prenatally as carrying an infant with Downs Syndrome. The woman was poorly educated and had a difficult time understanding the nature of the problem. She and her husband were living on a combined income that was barely above the poverty level. They were nonpracticing Catholics. She was told that the infant would have certain characteristic physical features. ( She was shown several pictures of Downs Syndrome children to help her understand) She was also told that the baby boy would have some unknown degree of mental retardation but would not suffer physically unless other problems arose that sometimes accompany Downs syndrome. She was told that there was no medical cure for the underlying condition and that legally she could have an abortion. The child would probably require special education and other supports to learn to adjust to his life with this condition.

As a member of a team, not as a solo counselor, what is the technologist's responsibility? Do the physicians and clergy have greater responsibility for offering advice? How directive should the team be in determining the outcome of the pregnancy? What should the cytogenetic technologist do?
 

Case 3

Frank Gold, a 23 year old man appeared at the Medical Records Department of a long -term care facility. This facility included skilled, intermediate, and long-term/custodial care as well as residential accommodations for the elderly. The young man asked for the medical records administrator for information about his maternal grandfather, who had lived at the facility for more than 20 years, when he was in his sixties and seventies, but had not died there. He had no information as to where or from what his grandfather had died and no on in his family would discuss the grandfather or what had happened to him. Mr. Gold was generally aware from his memory of his grandfather that he acted strangely , had a difficult time remembering things and near death did not even recognize his family members.

The young man was about to be married and was concerned about the mystery surrounding his grandfather's demise; he was especially interested in obtaining information relevant to genetic history, in view of his impending marriage. His mother had died of breast cancer three years previously at age 58, but Mr. Gold had been concerned that before her death she had begun to show early signs of premature senility. He had no idea whether her condition was related to his grandfather's but he was curious. He did not have any authorization form from his grandfather's next of kin ( Mr. Gold's Uncle) to obtain information from the patient record, as the knowledgeable family members had closed ranks and refused to discuss the grandfather. Sate law and institutional policy required a signed authorization form from the next of kin to release information from the medical record of a deceased patient. Should Mr. Gold be told?
   


Ryan McGuire

The decision to undergo genetic testing is a very personal one. It should also be voluntary, and someone should agree to the test only if he or she desires the information. No one who is considering a gene test should be pressured into it by relatives, health care providers, or anyone else.

There are certain benefits to deciding to take a gene test. Persons in high risk families live with troubling uncertainties about their own future as well as that of their children. A negative test, especially one that is strongly predictive, can create a tremendous sense of relief. A negative test, especially one that is strongly predictive, also may eliminate the need for frequent checkups and tests, which would save time and money. Also, a positive test can produce benefits as well. For instance, it can relieve uncertainty, and it can allow a person to make informed decisions about his or her future. Under the best of circumstances, a positive test creates an excellent opportunity for counseling and interventions to reduce risk. The prime example here is colon cancer. When tumors are caught early, chances for survival are greatest, and screening potentially could prevent thousands of cancer deaths a year. A positive gene test therefore sounds the alert to keep up regular screening practices and to maintain healthful lifestyle measures.

On the other hand, there are certain risks involved with deciding to get genetically tested. The physical risks of the gene test itself, usually no more than giving a blood sample, are minimal. Any potential risks have more to do with the way the results of the test might change a person's life. First, there is a large psychological impact created as a result of the gene test in that, there are emotions aroused by learning that one is or is not likely to develop a serious disease. Many people in disease families have already seen close relatives fall victim to the disorder. Thus, news that one does indeed carry the disease gene can elicit depression and even despair. Also, genetic testing can create a problem with family relations. Unlike other medical tests, gene tests reveal information not only about ourselves but about our relatives, and the decision to have a gene test, as well as the test results, can reverberate throughout the family. For instance, if a baby tests positive for sickle-cell trait, then it follows that one of his or her parents is a carrier. It is also a possibility that gene tests can inadvertently disclose family secrets involving paternity or adoption. Certain medical choices arise as a result of a genetic test. Someone who tests positive for a cancer susceptibility gene must make the decision of whether or not to opt for preventative or therapeutic measures that have serious long-term implications and are potentially dangerous or of unproven value. Finally, one risks his or her privacy when undertaking a gene test. Our genes hold an encyclopedia of information about ourselves and indirectly, about our relatives. The question here is who should be privy to this information? The concern here is that the test results might someday be used against a person. For example, some people have been denied health insurance, some have lost jobs or promotions, and some have been turned down for adoptions because of their gene status. Thus, might a genetic flaw constitute a preexisting condition that would be excluded from insurance coverage?

There is also a problem with interpreting the results of genetic tests. Too many doctors, insufficiently trained in genetics, also find that testing can be a mixed blessing. They become vulnerable to malpractice suits by giving faulty information, or none at all, on the implications of the test, or by failing to refer patients to properly trained genetic counseling specialists. To compound the problem, there are only about 1,000 of these specialists practicing in the U.S.

One of the effects of testing for predispositions will be to blur the boundaries between health and disease, creating new diagnoses of sick genotypes in healthy phenotypes. Other tests will introduce new subtleties into the diagnosis of those who are definitely ill. Cancers, for example, may be subdivided according to which particular genes for cellular self-restraint have gone wrong. Such differences may matter in that, some may respond to drugs much better than those with differing disease genes. Thus, by dissecting diseases genetically, it may be possible to match diagnosis to treatment much more effectively, and this represents the promising infant field of pharmacogenetics. Through this field many drugs can be re-evaluated, the design of clinical trials is likely to benefit, and so is our quality of life. Thus, it is evident that there are many factors to consider when thinking about genetic testing, and it is something that should not be rushed into.