Genetic testing , also known as DNA testing , allows the determination of bloodlines and genetic diagnosis of susceptibility to inherited diseases. In agriculture, a form of genetic testing known as progeny testing can be used to evaluate the quality of nursery stock. In population ecology, genetic testing can be used to track the genetic forces and species susceptibility of species.
In humans, genetic testing can be used to determine the offspring of a child (mother and father genetically) or in general a person's ancestor or biological relationship between humans. In addition to studying chromosomes to individual gene levels, genetic testing in a broader sense includes biochemical tests for possible genetic diseases, or mutant gene forms associated with an increased risk of developing a genetic disorder.
Genetic testing identifies changes in chromosomes, genes, or proteins. Various genetic tests have evolved over the years. In the past, major genetic tests searched for abnormal chromosome numbers and mutations that caused rare inborn disorders. Today, tests involve analyzing multiple genes to determine the risk of developing a particular disease or disorder, with a more common illness consisting of heart disease and cancer. Genetic test results can confirm or rule out a suspected genetic condition or help determine a person's chances of developing or passing on genetic disorders. Several hundred genetic tests are in use, and more are being developed.
Because genetic mutations can directly affect the structure of their encoded proteins, testing for certain genetic diseases can also be done by looking at their proteins or metabolites, or seeing colored or fluorescent chromosomes under a microscope.
Video Genetic testing
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Non-diagnostic testing includes:
- Forensic tests: Forensic tests use DNA sequences to identify individuals for legal purposes. Unlike the tests described above, forensic testing is not used to detect gene mutations associated with the disease. This type of test can identify crime or disaster victims, exclude or involve a crime suspect, or build a biological relationship between people (eg, father).
- Paternity Testing: This type of genetic test uses special DNA markers to identify similar or similar inheritance patterns among related individuals. Based on the fact that we all inherited half of our DNA from fathers, and half of mothers, DNA scientists tested individuals to find a matching DNA sequence on some very high differential markers to draw conclusions of linkage.
- Genealogy DNA test: To determine an ancestral or ethnic heritage for genetic genealogy
- Testing research: Research testing includes finding unknown genes, studying how genes work and advancing our understanding of genetic conditions. Test results performed as part of a research study are usually not available to patients or their health care providers.
Disease special
Many diseases have genetic components with tests already available. This list keeps changing with the addition of new test availability. The list below is just a few of the thousands of tests available.
- Iron overload Africa
Over-absorption of iron; accumulation of iron in vital organs (heart, liver, pancreas); organ damage; heart disease; cancer; liver disease; arthritis; diabetes; infertility; inability
- Alpha-1 antitrypsin deficiency
Obstructive pulmonary disease in adults; cirrhosis of the liver during childhood; when newborns or babies suffer from jaundice lasting for long periods (more than a week or two), enlarged spleen, ascites (fluid buildup in the abdominal cavity), pruritus (itching), and other signs of liver injury; people under 40 years of developing wheezing, chronic cough or bronchitis, shortness of breath after activity and/or showing other signs of emphysema (especially when non-smokers, not affected by known lung irritation, and when lung damage seems to lie low in the lungs); when you have a close family with a deficiency of antitrypsin alpha-1; when a patient has decreased A1AT levels.
- Apolipoprotein E-associated
Increased serum cholesterol and triglycerides; accelerated atherosclerosis, coronary heart disease; xanthoma skin; peripheral vascular disease; diabetes mellitus, obesity or hypothyroidism. The APOE gene is also associated with the development of complex genetic disorders such as Alzheimer's disease.
- Becker/Duchenne muscular dystrophy
Muscle weakness (rapidly progressive); often fall; difficulties with motor skills (running, jumping, jumping); progressive difficulties walking (walking ability may be lost by age 12); fatigue; intellectual backwardness (perhaps); bone deformity; chest and back (scoliosis); muscle deformity (heel contracture, leg, calf muscle pseudohypertrophy)
- Beta-thalassemia
Reduce the synthesis of the beta-hemoglobin chain; microcytic hypochromic anemia
- Factor II
Venous thrombosis; certain arterial thrombotic conditions; patients with deep venous thrombosis, pulmonary embolism, cerebral venous thrombosis, and premature ischemic stroke and also women with premature myocardial infarction; family history of early onset stroke, deep venous thrombosis, thromboembolism, pregnancy associated with thrombosis/embolism, hyperhomocysteinemia, and multiple miscarriages. Individuals with mutations are at increased risk of thrombosis in regulating use of oral contraceptives, trauma, and surgery.
- Factor V Leiden
Venous thrombosis; pulmonary embolism; transient ischemic attack or premature stroke; peripheral vascular disease, especially the lower extremities; occlusive disease; cerebral venous thrombosis; some spontaneous abortion; intrauterine fetal death
- Homocysteine ​​â € <â € <
Venous thrombosis; elevated levels of homocysteine ​​â € <â €
Independent risk factors for coronary artery disease, ischemic stroke, venous thrombosis (including osteonecrosis)
- Breast, ovarian and prostate cancers
Cancer cell division is uncontrolled
- Crohn's disease
Inflammation is limited to the large intestine; abdominal pain and bloody diarrhea; anal fistulas and peri-rectal abscesses can also occur
- Cystic fibrosis
Large amounts of abnormally thick mucus in the lungs and intestines; causing congestion, pneumonia, diarrhea and poor growth
- Deaf (non-syndromic)
Loss of innate hearing loss; -different, non-syndromic deaf
- Familial hypercholesterolemia
Xanthomas tendon; elevated LDL cholesterol; premature heart disease
- Fanconi anemia
Predisposing of acute myeloid leukemia; skeletal abnormalities; radial hypoplasia and vertebral defects and other physical disorders, bone marrow failure (pancytopenia), endocrine dysfunction, osteopenia/early onset osteoporosis and lipid abnormalities, spontaneous chromosomal damage compounded by exposure of DNA crosslinking agents.
- Fragile-X syndrome
Mental retardation or unknown learning aetiology; autism or autistic characteristics such as; women with early menopause. Subtle dysmorphism, facial jaw with prominent jaw and large ears, macroorchidism in postpartum men, behavioral abnormalities, due to lack of FMR1 in areas such as cerebral cortex, amygdala, hippocampus and cerebellum
- Friedreich's ataxia
Marked with progressive ataxia is slow; usually associated with distressed tendon reflexes, dysarthria, Babinski responses, and loss of position and vibration sensation
- Hereditary hemochromatosis
Over-absorption of iron; accumulation of iron in vital organs (heart, liver, pancreas); organ damage; heart disease; cancer; liver disease; arthritis; diabetes; infertility; inability
- Hirschsprung's Disease
Absence of ganglia in the intestine
- Huntington's Disease
Progressive disorders of motor, cognitive, and psychiatric disorders.
- Lactose Intolerance
Hypolactasia; persistent diarrhea; stomach cramps; bloated; nausea; fart
- Some endocrine neoplasia
MEN2A (which affects 60% to 90% of MEN2 families): Medullary thyroid carcinoma; Pheochromocytoma (adrenal gland tumors); Parathyroid adenoma (benign [non-cancerous] tumor) or hyperplasia (large size) of the parathyroid gland; MEN2B (which affects 5% of MEN2 families): Medullary thyroid carcinoma; Pheochromocytoma; Mucosal neuromas (benign tumors of neural tissue on the tongue and lips); Digestive problems; Problems of muscles, joints, and spine; Typical facial features; Familial medullary thyroid carcinoma (FMTC) (affecting 5% to 35% of MEN2 families): Medullary thyroid carcinoma alone
- Myotonic muscular dystrophy
It affects the skeletal and fine muscles as well as the eyes, heart, endocrine system, and central nervous system; Clinical findings, which include a continuum of mild to severe, have been categorized into three rather overlapping phenotypes: mild, classical, and congenital.
- Pseudocolinesterase deficiency
Pseudocolinesterase (also called butyrylcholinesterase or "BCHE") hydrolyzes a number of choline-based compounds including cocaine, heroin, procaine, and succinylcholine, mivacurium, and other rapid muscle relaxants. MCHATIONS in the BCHE gene cause a deficiency in the amount or function of proteins, which in turn results in delays in the metabolism of these compounds, which extend the effect. Succinylcholine is commonly used as anesthesia in surgical procedures, and a person with a BCHE mutation may suffer from prolonged paraylasis. Between 1 in 3200 and 1 in 5,000 people carrying the BCHE mutation; they are most common in Jewish Persian and Alaska Natives. In 2013 there are 9 genetic tests available.
- Sickle cell anemia
Degree of degree of haemolysis and intermittent episodes of vascular occlusion resulting in tissue ischaemia and acute and chronic organ dysfunction; complications including anemia, jaundice, a tendency to aplastic crisis, sepsis, cholelithiasis, and delayed growth. Diagnosis is suspected in infants or young children with painful swelling of the hands and feet, pallor, jaundice, pneumococcal sepsis or meningitis, severe anemia with enlarged spleen, or acute chest syndrome.
- Tay-Sachs Disease
Lipids accumulate in the brain; neurologic dysfunction; progressive weakness and loss of motor skills; decreased social interaction, seizures, blindness, and total weakness
- Variegate porphyria
Cutaneous photosensitivity; acute neurovisceral crisis
Maps Genetic testing
Medical procedure
Genetic testing is often performed as part of genetic counseling and by mid-2008 there were more than 1,200 clinically available genetic tests. Once a person has decided to proceed with genetic testing, a medical geneticist, a genetic counselor, primary care physician, or specialist may order tests after obtaining informed consent.
Genetic testing is performed on blood, hair, skin, amniotic fluid (fluids that surround the fetus during pregnancy), or other tissues. For example, a medical procedure called buccal smear uses a small brush or cotton to collect cell samples from the inner surface of the cheek. Alternatively, a small amount of saline mouthwash can be stirred in the mouth to collect cells. Samples are sent to laboratories where technicians look for specific changes in chromosomes, DNA, or proteins, depending on the suspected interference, often using DNA sequencing. The laboratory reports written test results to one's physician or genetic counselor.
A newborn routine screening test is performed on small blood samples obtained by piercing the heel of a baby with a lancet.
Risks and limitations
The physical risks associated with most genetic tests are very small, especially for tests that require only a blood sample or buccal smear (a procedure that takes cell samples from the inner surface of the cheek). The procedures used for prenatal testing carry a small but not negligible risk of losing a pregnancy (miscarriage) because they require amnionic fluid samples or tissues from around the fetus.
Many of the risks associated with genetic testing involve emotional, social, or financial consequences of test results. People may feel angry, depressed, anxious, or feel guilty about their results. The potential negative impact of genetic testing has led to increased recognition of "the right to not know". In some cases, genetic testing creates tension within the family because the results may reveal information about other family members other than the person being tested. The possibility of genetic discrimination in work or insurance is also a concern. Some individuals avoid genetic testing for fear it will affect their ability to buy insurance or find work. Current health insurance does not require applicants for coverage to undergo genetic testing, and when insurance confronts genetic information, it is subject to the same privacy protection as other sensitive health information. In the United States, the use of genetic information is governed by the Genetic Information Discrimination Act (GINA) (see discussion below on the section on government regulation).
Genetic testing can only provide limited information about inherited conditions. Tests often can not determine whether a person will show symptoms of the disorder, how severe the symptoms will occur, or whether the disorder will develop over time. Another major limitation is the lack of treatment strategies for many genetic disorders after they have been diagnosed.
Another limitation for genetic testing for hereditary-related cancers, is a variant that is not known clinically. Since the human genome has more than 22,000 genes, there are 3.5 million variants in the average human genome. This unknown variant of clinical significance means there is a change in the DNA sequence, but the increase for cancer is unclear as it is unknown whether changes affect gene function.
A geneticist can explain in detail the benefits, risks, and limitations of a particular test. It is important that everyone who is considering genetic testing understands and weighs these factors before making a decision.
Other risks include accidental findings - the discovery of some problems that may be found when looking for something else. In 2013, the American College of Medical Genetics and Genomics (ACMG), certain genes are always included every time the genome sequencing is done, and that the laboratory should report the results.
Genetic testing directly to consumers
A direct genetic test to the consumer (DTC) is a type of genetic test that can be accessed directly to consumers without having to go through professional health care. Usually, to get a genetic test, health care professionals (such as doctors) get their patients' permission and then order the desired test. The genetic test DTC, however, allows consumers to skip this process and order the DNA test itself.
There are various DTC tests, ranging from tests to breast cancer alleles to mutations associated with cystic fibrosis. The benefits of DTC testing are the accessibility of tests to consumers, the promotion of proactive health care, and the privacy of genetic information. Possible additional risks of DTC testing are lack of government regulation, potential misinterpretation of genetic information, issues related to underage testing, data privacy, and downstream costs for public health care systems.
Controversy
The DTC genetic test has become controversial because of the outspoken opposition in the medical community. Critics of DTC testing are against the risks involved, unregulated advertising and marketing claims, and lack of overall government oversight.
DTC testing involves many of the same risks associated with any genetic test. One of the more obvious and dangerous of these is the possibility of misreading the test results. Without professional guidance, consumers can potentially misinterpret genetic information, causing them to be deceived about their personal health.
Some advertising for DTC genetic testing has been criticized for conveying exaggerated and inaccurate messages about the relationship between genetic information and disease risk, exploiting emotion as a sales factor. An advertisement for the BRCA-predictive genetic test for breast cancer states: "There is no stronger antidote to fear than information."
Ancestry.com, the company that provides DNA DTC testing for genealogical purposes, has reportedly allowed unsecured searches for their database by police investigating the killings. The search without the letter leads to a search warrant for forcing DNA collection from a New Orleans filmmaker; But he was not suited for a murder suspect.
Government regulation in the United States
Currently, the US does not have strong federal regulations that moderate the DTC market. Although there are several hundred tests available, only a handful are approved by the Food and Drug Administration (FDA); it is sold as a home test kit, and is therefore considered a "medical device" in which the FDA can assert jurisdiction. Other types of DTC tests require customers to send DNA samples for testing; it is difficult for the FDA to exercise jurisdiction over these types of tests, since actual testing is completed in the provider's laboratory. As of 2007, the FDA has not been officially proven by scientific evidence of claimed accuracy from the majority of genetic tests directly to consumers.
With regard to genetic testing and information in general, the laws in the United States called the Genetic Information Disqualification Act prohibit group health plans and health insurance providers from denying protection to healthy individuals or charging a higher premium to such persons solely based on genetic predispositions to develop future illnesses. The law also prohibits employers from using individual genetic information when making hiring decisions, dismissals, job placements, or promotions. The law, the first of its kind in the US, was adopted by the United States Senate on 24 April 2008, in a 95-0 vote, and signed into law by President George W. Bush on 21 May 2008. It came into force on 21 November 2009.
In June 2013, the US Supreme Court issued two decisions on human genetics. The court dropped patents on human genes, opening up competition in the field of genetic testing. The Supreme Court also ruled that police were allowed to collect DNA from people arrested for serious offenses.
In popular culture
Some possible future ethical issues of genetic testing are considered in the science fiction film Gattaca , the novel Next , and the science fiction anime series "Gundam Seed". Also, some movies that include genetic testing topics include The Island , Halloween: Michael Myers Curse , and series Resident Evil .
Ethics
Pediatric genetic testing
The American Academy of Pediatrics (AAP) and the American College of Medical Genetics (ACMG) have provided new guidelines for ethical issues of pediatric genetic testing and childhood screening in the United States. Their guidelines state that doing pediatric genetic testing should be a child's primary concern. In hypothetical situations for adults getting genetically tested 84-98% expressed interest in getting tested genetically for cancer predisposition. Although only half are at risk will be tested. AAP and ACMG recommend delaying genetic testing for late-onset to adulthood conditions. Unless diagnosing genetic disorders during childhood and starting early interventions can reduce morbidity or mortality. They also stated that with parent or guardian testing permission for asymptomatic children at risk of a childhood onset condition is an ideal excuse for genetic testing pediatrics. Tests for pharmacogenetics and newborn screening can be accepted by AAP and ACMG guidelines. The histocompatibility testing guidelines state that it is permissible for children of all ages to have network compatibility testing for immediate family members but only after psychosocial, emotional and physical implications have been explored. With donor advocates or similar mechanisms should be in place to protect minors from coercion and to protect minor minor interests. Neither AAP nor ACMG advocate the use of genetic kits directly to consumers and homes because of the accuracy, interpretation and control of the test content. The guidelines also state that if a parent or guardian should be encouraged to inform their child about the outcome of a genetic test if a minor is age appropriate. If small maturity and yield demand, the request must be respected. Although for ethical and legal reasons, healthcare providers should be cautious in giving minors a predictive genetic test without the involvement of a parent or guardian. The AAP and ACMG guidelines state that health care providers have an obligation to notify parents or guardians of the implications of the test results. To encourage patients and families to share information and even offer help in explaining outcomes to expand families or refer them to genetic counseling. AAP and ACMG state that all types of predictive genetic testing for all types are the best offers with genetic counseling offered by Clinical genetics, genetic counselors or healthcare providers.
Israel
Israel uses DNA tests to determine whether people qualify for immigration. The policy in which "many Jews from the Former Soviet Union ('FSU') were asked to provide DNA confirmation of their Jewish heritage in paternity tests to immigrate as Jews and to be citizens under Israeli Reversion Law" has caused controversy..
Cost
The cost of genetic testing can range from less than $ 100 to over $ 2,000. It depends on the complexity of the test. Costs will increase if more than one test is required or if some family members are tested for additional results. Fees may vary by state and some states cover a portion of the total cost.
Starting from the date of sampling, the results may take weeks to months, depending on the complexity and level of testing performed. Results for prenatal testing are usually available more quickly because time is an important consideration in making decisions about pregnancy. Before testing, a physician or genetic counselor who requests a particular test may provide specific information about the costs and timeframes associated with the test.
See also
- DNA profile
- Personal medicine
- Eugenics
- Full Genome Ordering
- Whole Genome Sequencing
- Entire Order Express
- Genetic counseling
- List of genetic disorders
- List of genetic genealogy topics
- Non-dad event
References
This article combines public domain material from the United States Department of Health and Public Service documents, "What are the risks and limitations of genetic testing?". This article incorporates public domain material from the United States Department of Health and Public Service documents, "What are the costs of genetic testing, and how long to get results?".
Source of the article : Wikipedia
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