Assignment On Gene Testing-PRAVEEN

Introduction

Gene Testing

Gene testing is also called a DNA test where it uses the most newest and relevant techniques to test genetic disorders as where it involves examination of DNA molecule. There are other genetic tests as well. It includes tests for gene products which are like enzymes and other proteins. And when the gene can’t be directly indentified, techniques such as linkage analysis or indirect analysis should be used. Each humans DNA is very unique (except for identical twins). DNA fingerprint or individual identification can also be known by genetics tests. Each human being carries two copies of gene, where one inherited from the mother and another one is from the inherited father. Human genome is believed to contain around 20000 to 25000 genes. Gene testing identifies the changes in a chromosomes, genes and protein. Genetic testing mainly used to find changes in inherited disorders. When interpreting the results of generic, false positive and false negative test results should take under consideration. Hundreds of generic are currently in use and day by day many others are being developed.

Types of Gene Testing

Newborn screening

Newborn screening testing is done for every newborn babies for some harmful and fatal disorders that can be treated and where it is difficult detect clinically. This screening can detect metabolic disorders that have connections in body nutrients. Next the screening can detect problems with hormones in the blood. Blood sample are collected from the infant’s heel on a well designated filter paper and then tested for disorders. Early treatment can make a healthy development.

Robert Guthrie is the one who developed a blood test to find out a metabolic disorder of a disease called phenylketonuria (PKU). People with PKU has deficiency in enzyme needed to process amino acid phenylalanine where it is needed for normal growth of childrens.

Techniques that are used are by collecting blood samples on a special designed filter paper. The filter paper contains a form where it has the details of the parents and baby(infant). Information that includes in the filter paper is as the baby’s time and date of birth,time and date of the sample collection,the baby’s weight and gestational weight. Blood transfusion and and nutrients of the baby is also stated in the form.Samples are collected between 24 hours and 7 days of when the baby was

born. 

Results should be reported as soon as possible. If everything seems to be normal then a letter will be sent to the hospital. If there’s abnormality evalution of the baby will be taken care by a specialist physcian.

Types of Diseases that can be detected is as:

·         Sickle Cell Disease

·         Biotinidase Deficiency

·         Congenital Adrenal Hyperlasia

·         Maple Syrup Urine Disease

·         Tyrosimea

·         Cystic Fibrosis

·         MCAD Deficiency

·         Toxoplasmosis

Carrier Testing

A person who has a change in one single gene in a recessive disease is called as an carrier. Two changes is required to make the changes to produce disease. Due to that the person remains well and logically unaware of his status of body. When there is two carriers has a child, its likely that 25% of the child will be affected. This is different when one carrier has a child with a non carrier, they child will likely not a have disease

.

There are two ways where genetic tests used. One way of carrier testing is by direct analysis of the gene transmission. The genes are extracted from blood cell and they are also tested for mutation. Test for the amount or activity of a gene products that normally prevent disease is the second way. The choices of the test always depend on the ability to detect as much as carriers as possible.

Disease of an baby can be learned before birth occur by pretanal diagnosis if the carriers decided to have children. Small sample of placenta which is between 10 to 12 weeks of pregnancy or small sample of fluid that bathes the baby which is between 14 to 20 weeks can be use as a prenatal diagnosis. Gene testing is used to find out whether the baby has the same disease as the carriers. There are carriers who decide not to have baby which having same or different carrier as them.

The test can detect all the mutation or carriers that present. Testing laboratory uses procedures to assure a high sterile and quality level. There are sometimes where the results can’t be obtain, new sample is collected for the testing again.

The results usually can be obtained in 2 weeks to 3 weeks time from where the specimen has be collected. If you are believe to be a carrier then a genetic counselor will call u soon to update you regarding your state

Diagnostic Testing

Diagnostic testing is a test on any kind of medical test that present to help in the diagnosis or detection in any kind of disease. Example of diagnostic testing are like to diagnose a disease, to measure the time of progress and recovery of a specified disease and also to ensure that a particular person if free from disease.

Some of the test required a simple physical examination which needed simple tools in the hand of a physician. Some other tests are held in sterile operating theatre environment by medical technologist. There are also tests that are sent to a pathology lab for further analysis such as tissue or body fluids. Chemical tests like urine pH can be easily measured in doctor’s office. A dead person’s test is called as autopsy or post-mortem.

Test results are measured before, during and after each assay is conducted. Test results are very dependant. Production of a good results requires a fully specified program that includes quality control, quality assessment and quality assurance.

Classification of Medical Test

1.     Invasive procedure - a procedure where it involves invasion of the internal body by making a break or incision in the skin, or by inserting a tube or a device into an internal body cavity or organ.

2.     Minimal Invasive   - a procedure where it is less invasive than open surgery used for the same purpose.

3.     Non-Invasive procedure - a procedure when no break in the skin is created and there are no contact with the mucosa, internal body capacity beyond the natural body origin.

Test values are also determined in diagnostic testing. There are two, one is accuracy characteristics and precision characteristics. Accuracy means test with its corresponded value and precision means test of reproducibility when repeated on the same sample.

Types of Medical Tests

Consulting Room Test:

·         Measuring blood pressure

·         Breath tests

·         Eye examination

·         Hearing test

·         Weighing and measuring height

·         Vaginal examination

·         Reflex tests.

Laboratory Analysis:

·         Blood tests

·         Saliva tests

·         Hair tests

·         Stool tests

·         Genetic testing

Forensic Testing

Forensic DNA testing uses advanced testing techniques to help the legal system in plenty of cases. This testing is apparently used in questions to identify like placing a criminal on a crime scene or establishing paternity. Body fluids, skin or even hair  are used as an samples for forensic DNA testing. It is to identify the identity of a person using their genetic code which is found during a scene.

Distinct code is embedded in each human being’s DNA. Although relatives or cousins have similar genetic codes, evidence suggest that any two people could have an identical code. Sample such as mouth swab from a suspect and comparing it with the physical evidence that found in the crime scene, forensic scientists can determine if the DNA sample is match or it doesn’t.

Many types of different methods are used in forensic DNA testing depending on the type of samples that obtained and the important to tests. In paternity testing, forensic scientist may look at the composition of the Y-Chromosome. Y-Chromosome is genetically passes from the father to the child. On the other hand, there are methods involve comparing specific repeating patterns found in DNA or by examining in the nucleus of the cell.

Paternity Testing

The DNA test that is most accurate and precise test to determine blood among people. Though gene testing is the most reliable standard, older methods also exist, including ABO blood group typing, analysis of various other proteins and enzymes, or using human leukocyte antigen antigens. The current techniques for paternal testing are using polymerase chain reaction (PCR) and restriction fragment length polymorphism.

This way of testing is accepted all over the world in such governmental institution nationwide like Immigration. The DNA test provided by the genetech confirms or denies fatherhood. Every test provides an exclusion if the test shows no ties at all or inclusion if ties are established between individuals. The results completely confidential and certified by public notary.

Using a mouth sponge to obtained the sample via DNA test is a painless process, A blood test is performed only when required by an entity when complexity of the case requires it; however, both tests offer the same confidence level.

Predictive and presymptomatic genetic testing

An evaluation from a geneticist, psychologist, psychiatrist, neurologist, and/or a social worker should be done to evaluate your need or reason for wanting to have a predictive genetic test done. The type of information presented during pretest counseling can include information about the disorder, the predictive test, possible psychological impacts, and the limitations and substantial elements of uncertainty that are linked to the test.

Predictive and presymptomatic genetic testing is done to detect for gene mutations that can leave a person susceptible to disease later on in life. For this type of genetic testing, knowing the medical conditions that are present in your family history is important because it can help evaluate your risk for developing a certain disease. A person who undergoes a predictive genetic test is not a patient because there would be no need for medical care at the time that the genetic test is done.

However, a predictive genetic test that shows a person has a gene mutation that could lead them to developing a certain genetic disease can help establish which early screening tests should be done. Some experts have argued that there should be a medical reason to carry out a predictive genetic test. Therefore, it has been stressed that the request for a test should be voluntary and come from a person who understands the implications of the test without any external pressure from family.

Cytogenetic tests evaluate whole chromosomes from the nucleus of the cell for changes in number or structure. Cytogenetic testing is often the first tier of genetic testing for a number of clinical situations. These situations include assessment of a developmentally delayed child, evaluation of a cancerous tumour, or amniocentesis to detect chromosomal anomalies in a fetus. Prenatal testing for Down syndrome uses cytogenetic testing to identify an extra copy of all or part of chromosome 21.

  

 Advantages

There are many advantages on gene testing. It can lead to early diagnosis and prevention of disease. Further than that, it can help the advancement of medical understanding any tearments of disease.

Carrier testing can help couples to be screened for carrier genes so that they can make an decision whether to have a child or not. If both parents are a particuar gene carriers then they are more likely to give birth to a child having a specific disease or disorder. 

There are diseases that leads to life time suffering or even an early death after birth. Example’s of genetic screening of newborns that can help to detect early diseases are like sickle cell anemia and phenylketonuria. Individuals can avoid inherited diseases that run through families with genetic testing. Early comfirmation of disease can help affected people to seek proper treatment and take appropriate preventive measurement.

Gene testing can identify genes that put people at risk for developing certain disorders and diseases. A negative result in susceptibility testing can provide relief for people who have continual examinations such as colonoscopies because of the prevalence or related disease in their families. Such predictive genetic testing can help people with confirmed susceptibility take preventive measures. For example,people who are having risks can have frequent medical check up. Gene testing also can clarify your cancer risk explains why you or other family members have developed cancer. Even the early detection of breast cancer can be tested.

Disadvantages

A positive feedback on genetic testing does not mean a person will never develop a disease. Example like blood test that womans go during pregnancy will indicate that the baby or infant will have certain disease conditions but will not say for sure whether the baby or infant is affected. Those that test positive for a genetic disorder but may not develop it may be worrying unnecessarily and going for treatments they don't need. You will face emotional distress once you find out the results. This can also affect your family and friends emotionally.

In some state, insurance companies depends on genetic testing. If a person has taken genetic testing, some insurance companies may drop that person or raise her rates. Basically, in the insurance company’s mind, a person who has received genetic testing is known as a high-risk insurance client.

 Autonomy

Gene testing refers to the right of a person to be informed whether they wished to be tested and whether they wish to know about the details of the outcome of the testing. Autonomy also emphasis on the right of an individual to control and to avoid on others interfering with their respective life decisions based on genetic informations. It also implies the right of individuals to control of genetic material given analysis.

An individual has right to be informed of the nature of their condition, the potential risks and benefits of a test and treatment

Genetic disease plays an increasingly important role in doctor’s daily practice. Concerns about genetic testing in pediatric medicine specifically address the issues of consent and confidentiality.Particular attention has been given to the implications of predictive testing for

carrier testing, and newborn screening.

The issue of prenatal testing and selective abortion has never received public acceptance. However, the tendency to know in this area is rapidly growing. In part this is a result of concerns about the rate of development in genetic knowledge and questions as to its application. There will be a huge increase of conditions or features for which we will be able to screen, some of which could hardly be described. Further, for some time now, people with disabilities have had concerns about the practice of prenatal testing and selective abortion. Prenatal testing allow couple to make choices about the continuation of pregnancy.

Autonomy also specefied that decisions must be voluntary. The decision to have or not have a genetic test is widely believed to be a choice each person should make based on his or her own values and preferences.

One of the most important components of informed decision is the discussion that takes place before taking a genetic test. It is helpful to consider that individuals may be members of a family who make choices as a group, and that strong influences.

Do Good And Do No Harm

The discovering of genes along with disease together with an increasing genetic technologies has made a big difference in improving identifications of individuals who are in high risk. Genetic screening could have great value if used properly to help people take preventive measures to avoid suffering from some diseases. The first type of genetic screening used was screening of newborn children for PKU deficiency. If the new born is found to have PKU deficiency, they can be put on a special diet, and will not suffer from severe mental retardation.

Genetic screening also works out economically, because it is cheaper to treat patients before serious damage is done to them by a genetic disease. If screening shows the person is at risk, advise can be given on how to lower risk.

It has been found that many common cancers such as lung, breast, and colon develop by step- wise accumulation of mutations affecting many genes. The disease include the loss of some suppressor genes which inhibit cell growth. Genetic screening may help predicting a cancer, and can be used to warn people to avoid agents that causes more mutations like smoking.

Justice

Justice is the assurance that people receive fair and equal treatment. In genetic testing, the key elements of justice are similar to genetic services to all individuals. In addition, some genetic tests, such as preimplantation testing, are performed at few health centers, are very expensive, and are usually not covered by insurance.

Furthermore, for some genetic tests, the ability of a clinician to use results of a genetic test to predict risk for a specific disorder may vary for different ethic populations. Certain disorders are more commonly associated with specific ethnic groups, even though persons from other ethnic groups. For some disorders, the ability to identify carrier status will vary according to ethnicity. 

Ethical Consideration

Gene testing creates many chances to find out an disease and also to diagnose. However not all the test conducted will give a positive result. As an example, carrier testing can identify couples who are carriers. When there are risks detected from the parents, there are tests which can be performed to determind whether the child has inherited diseases from the parents (Prenatal Testing or Newborn Testing) . If the fetus has inherited dieases from the parents the severity can’t be predicted at that vary moment. Ethical consideration that involves in parents during this time involves like decison to continue or to end pregnancy without having a proper information on the particular disease.

Further more, not all conditions can be treated fully. Another consideration is the possibility that the gene testing tests could be inaccurate.When there is a positive outcome on a gene test taken, it can lead the parents to undergo more specific gene tests as well to confirm the condition presents in a fetus or infant. There are not many treatments available before birth. Thus this may cause ethical consideration for couples where they will not wan to pursue for gene testing (Prenatal Testing or Newborn Testing) at all. At this moment, the parents will be more concern on the possibility of the birth of baby.

Gene tests, example like screening tests will provide an false-positive and false-negative outcome. Most womans who receive an false-positive result can make them to undergo more tests and on the other hand they might even do pregnancy abortion. In fact, there are still parents who give birth to a child with a Down Syndrome disease even if they receive a negative outcome.

Gene tests can also finds out the mutations of genes and it can only predicts increased risk of diseases not the certainity of the diseases. Ethical consideration that happends here can lead to decisions that can be reversed. Removal of certain tissues in body based on genetic tests that are not diagnostic is defined as meeting the goals and doing avoiding harm.

Gene testing for some conditions for which there are no treatments to date has the potential to cause psychological harm to any individuals who has to know that they have contact with a certain disease. 

Gene discrimination is when individuals treats a person differently because of genetic differences. Persons who qualified for genetic testing knows that it is very more difficult to obtain insurance. The confidential of individuals medical information is important, but it may not be enough to eliminate the risk of discrimination against persons who have a positive result on a genetic test.

Consequences of violation in gene testing

For many years, the advancement in the technology of gene testing has made it easier for us to have an insight into the human health details. As such, we are more in control of our genetic destinies. While it is agreed that gene testing has its own advantages, but like 2 sides of a coin, it also has its disadvantages.

Gene testing has made it possible for parents to-be to test their unborn foetuses to check on possible diseases or characteristics due to a faulty gene. But what many fail to realize is that detection of a faulty gene or an abnormality may not provide all information about the severity of the condition. In these types of cases, the parents to-be may choose to terminate the pregnancy. Gene testing can also be used to determine the sex of a baby by checking the chromosomes. Many times, there are requests to use the technology to ensure that parents to-be have a baby only of the desired sex. With that, begins the trend of selective breeding that conflict with moral and religious beliefs.

Gene testing also allows analysis of individual genetic make-up. This can pose a major disadvantage for the individual as information discovered through this analysis can be used against an individual. For an example, if insurance companies know the likelihood of a person developing a certain condition, this information can be used to determine the eligibility for basic health insurance. This is definitely an infringement to human rights.

Employers may also use information derived from gene testing to identify employees whose has certain genetic traits and choose not to employ them based on the information. This is because information derived from gene testing can be used to distinguish between applicants for jobs in terms of their ability to remain productive or even ability to take a minimum sick leave. Once such form of discrimination was also practiced by the U.S Air Force Academy even before gene testing was widely known. The Academy refused to accept members carrying the sickle cell anaemia gene.

In cases of adoption, a child’s genetic status may have implications on the child and the adoptive parents. Providing such information will surely influence whether or not the adoption proceeds. The use of gene testing information in this way is a form of disrespect of the child, and also violates the child’s right to choose whether or not to undergo gene testing on reaching adulthood, which causes a breach in the child’s genetic privacy.

When individuals go for gene testing, the data collected, be it for research purpose or health purpose, has a tendency to be misused for a purpose other than initially intended. In addition, genetic determinism is also one of the disadvantages that are posed by the technology of gene testing. Genetic determinism is the belief that behavioural and personality characteristics of an individual, such as intelligence or criminal behaviour, are mostly a function of genes.

It must be understood by all parties that results of gene testing in most cases only reflect possibilities rather than certainties. As such, it is unfair for an individual to be discriminated based on the results of their gene test.

The are many disadvantages that is posed by gene testing, but this can be minimalized with more stringent legislation to prevent unfair discrimination and also in educating the community about the risks and harms posed in the misuse of gene testing.

Conclusion

Genetic testing promises to become a larger part of primary care practice. Physicians must be familiar with the appropriate uses of genetic testing for their patients and with current information resources that will allow them to convey reliable information.

For each patient with an inherited disease, the practitioner must be able to define his or her role and that of the genetics professional by becoming familiar with the elements of a genetic consultation.

  

References

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