Examine individual changes

''''Genetic testing''' (also called [[DNA]]-based tests) is among the newest and most sophisticated of techniques<ref>Human Genome Project Information. [http://www.ornl.gov/sci/techresources/Human_Genome/medicine/genetest.shtml Gene Testing]</ref> used to test for genetic disorders which involves direct examination of the [[DNA molecule]] itself. Other genetic tests include biochemical tests for such gene products as [[enzyme]]s and other [[protein]]s and for microscopic examination of stained or fluorescent chromosomes. Genetic tests are used for several reasons, including: * identifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to be expressed, these are some examples: * preimplantation genetic diagnosis (see the side bar, Screening Embryos for Disease){{clarify |reason=What sidebar? |date=August 2012}} * [[prenatal diagnosis|prenatal diagnostic testing]] * [[newborn screening]]!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!#AESq4es5sr555 * [[Genealogical DNA test]] (for genetic genealogy purposes) * presymptomatic testing for predicting adult-onset disorders such as Huntington's disease * presymptomatic testing for estimating the risk of developing adult-onset cancers and Alzheimer's disease * confirmational diagnosis of a symptomatic individual * forensic/identity testing Genetic testing allows the [[Genetics|genetic]] [[medical diagnosis|diagnosis]] of vulnerabilities to inherited [[diseases]], and can also be used to determine a child's paternity (genetic father) or a person's [[ancestry]]. Normally, every person carries two copies of every [[gene]] (with the exception of genes related to sex-linked traits, which are only inherited from the mother by males), one inherited from their mother, one inherited from their father. The [[human genome]] is believed to contain around 20,000 - 25,000 genes. In addition to studying [[chromosomes]] to the level of individual genes, genetic testing in a broader sense includes [[biochemical]] tests for the possible presence of genetic diseases, or mutant forms of genes associated with increased risk of developing genetic disorders. Genetic testing identifies changes in [[chromosomes]], genes, or proteins.<ref>{{cite web|url=http://www.ghr.nlm.nih.gov/handbook/testing/genetictesting |title=What is genetic testing? - Genetics Home Reference |publisher=Ghr.nlm.nih.gov |date=2011-05-30 |accessdate=2011-06-07}}</ref> Most of the time, testing is used to find changes that are associated with inherited disorders. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a [[genetic disorder]]. Several hundred genetic tests are currently in use, and more are being developed.<ref>{{cite web|url=http://www.nlm.nih.gov/medlineplus/genetictesting.html |title=Genetic Testing: MedlinePlus |publisher=Nlm.nih.gov |date= |accessdate=2011-06-07}}</ref><ref>{{cite web |url=http://www.eurogentest.org/patient/public_health/info/public/unit3/DefinitionsGeneticTesting-3rdDraf18Jan07.xhtml |title=Definitions of Genetic Testing |accessdate=2008-08-10 |work=Definitions of Genetic Testing (Jorge Sequeiros and Bárbara Guimarães) |publisher=EuroGentest Network of Excellence Project |date=2008-09-11 }} {{Dead link|date=September 2010|bot=H3llBot}}</ref> Since genetic testing may open up ethical or psychological problems, genetic testing is often accompanied by [[genetic counseling]].{{Citation needed|date=November 2010}} ==Types== Genetic testing is "the analysis of, [[chromosome]]s (DNA), proteins, and certain [[metabolites]] in order to detect heritable disease-related [[genotype]]s, [[mutation]]s, [[phenotype]]s, or [[karyotype]]s for clinical purposes."<ref name="pmid9381169">{{cite journal |author=Holtzman NA, Murphy PD, Watson MS, Barr PA |title=Predictive genetic testing: from basic research to clinical practice |journal=Science |volume=278 |issue=5338 |pages=602–5 |year=1997 |month=October |pmid=9381169 |doi= 10.1126/science.278.5338.602|url=http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=9381169}}</ref> It can provide information about a [[person]]'s genes and chromosomes throughout life. Available types of testing include: * [[Newborn screening]]: Newborn screening is used just after birth to identify genetic disorders that can be treated early in life. The routine testing of infants for certain disorders is the most widespread use of genetic testing—millions of babies are tested each year in the United States. All states currently test infants for [[phenylketonuria]] (a genetic disorder that causes [[mental illness]] if left untreated) and [[congenital]] [[hypothyroidism]] (a disorder of the [[thyroid]] gland). * [[Diagnostic testing]]: Diagnostic testing is used to diagnose or rule out a specific genetic or chromosomal condition. In many cases, genetic testing is used to confirm a diagnosis when a particular condition is suspected based on physical mutations and symptoms. Diagnostic testing can be performed at any time during a person's life, but is not available for all genes or all genetic conditions. The results of a diagnostic test can influence a person's choices about health care and the management of the disease. * [[Carrier testing]]: Carrier testing is used to identify people who carry one copy of a gene mutation that, when present in two copies, causes a genetic disorder. This type of testing is offered to individuals who have a family history of a genetic disorder and to people in ethnic groups with an increased risk of specific genetic conditions. If both parents are tested, the test can provide information about a couple's risk of having a child with a genetic condition. * Prenatal testing: Prenatal testing is used to detect changes in a [[fetus]]'s genes or chromosomes before birth. This type of testing is offered to couples with an increased risk of having a baby with a genetic or chromosomal disorder. In some cases, prenatal testing can lessen a couple's uncertainty or help them decide whether to [[abortion|abort]] the pregnancy. It cannot identify all possible inherited disorders and [[birth defect]]s, however. * [[Preimplantation genetic diagnosis]]: Genetic testing procedures that are performed on [[human embryo]]s prior to the implantation as part of an [[in vitro fertilization]] procedure. * [[Predictive testing|Predictive and presymptomatic testing]]: Predictive and presymptomatic types of testing are used to detect gene mutations associated with disorders that appear after birth, often later in life. These tests can be helpful to people who have a family member with a genetic disorder, but who have no features of the disorder themselves at the time of testing. Predictive testing can identify mutations that increase a person's chances of developing disorders with a genetic basis, such as certain types of [[cancer]]. For example, an individual with a mutation in ''[[BRCA1]]'' has a 65% cumulative risk of [[breast cancer]].<ref>http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12677558</ref> Presymptomatic testing can determine whether a person will develop a genetic disorder, such as [[hemochromatosis]] (an iron overload disorder), before any signs or symptoms appear. The results of predictive and presymptomatic testing can provide information about a person’s risk of developing a specific disorder and help with making decisions about medical care. * [[Forensic genetics|Forensic testing]]: Forensic testing uses DNA sequences to identify an individual for legal purposes. Unlike the tests described above, forensic testing is not used to detect gene mutations associated with disease. This type of testing can identify crime or catastrophe victims, rule out or implicate a crime suspect, or establish biological relationships between people (for example, paternity). * [[Parental testing]]: This type of genetic test uses special DNA markers to identify the same or similar inheritance patterns between related individuals. Based on the fact that we all inherit half of our DNA from the father, and half from the mother, DNA scientists test individuals to find the match of DNA sequences at some highly differential markers to draw the conclusion of relatedness. * Research testing: Research testing includes finding unknown genes, learning how genes work and advancing our understanding of genetic conditions. The results of testing done as part of a research study are usually not available to patients or their healthcare providers. *[[Pharmacogenomics]]: type of genetic testing that determines the influence of genetic variation on drug response. ==Medical procedure== Genetic testing is often done as part of a genetic consultation and as of mid-2008 there were more than 1,200 clinically applicable genetic tests available.<ref name=A-Hawkins2008>{{Cite news |last=Allingham-Hawkins |first=Diane |date=2008-08-01 |accessdate=2008-09-23 |title=Successful Genetic Tests Are Predicated on Clinical Utility |periodical=Genetic Engineering & Biotechnology News |publisher=Mary Ann Liebert |volume=28 |issue=14 |pages=6, 9 |url=http://www.genengnews.com/articles/chitem.aspx?aid=2544 |issn=1935-472X }}</ref> Once a person decides to proceed with genetic testing, a medical geneticist, genetic counselor, primary care doctor, or specialist can order the test after obtaining [[informed consent]]. Genetic tests are performed on a sample of [[blood]], [[hair]], [[skin]], [[amniotic fluid]] (the fluid that surrounds a fetus during pregnancy), or other tissue. For example, a [[medical procedure]] called a buccal smear uses a small brush or cotton swab to collect a sample of cells from the inside surface of the cheek. Alternatively, a small amount of saline [[mouthwash]] may be swished in the mouth to collect the cells. The sample is sent to a laboratory where technicians look for specific changes in chromosomes, DNA, or proteins, depending on the suspected disorder. The laboratory reports the test results in writing to a person's doctor or genetic counselor. Routine [[newborn]] screening tests are done on a small blood sample obtained by pricking the baby's heel with a [[Blood lancet|lancet]]. ===Interpreting results=== The results of genetic tests are not always straightforward, which often makes them challenging to interpret and explain. May not always be correct. When interpreting test results, healthcare professionals consider a person’s medical history, family history, and the type of genetic test that was done. In some cases, a negative result might not give any useful information. This type of result is called uninformative, indeterminate, inconclusive, or ambiguous. Uninformative test results sometimes occur because everyone has common, natural variations in their DNA, called [[Polymorphism (biology)|polymorphisms]], that do not affect health. If a genetic test finds a change in DNA that has not been associated with a disorder in other people, it can be difficult to tell whether it is a natural polymorphism or a disease-causing mutation. An uninformative result cannot confirm or rule out a specific diagnosis, and it cannot indicate whether a person has an increased risk of developing a disorder. In some cases, testing other affected and unaffected family members can help clarify this type of result. ==Risks and limitations== The physical risks associated with most genetic tests are very small, particularly for those tests that require only a blood sample or buccal smear (a procedure that samples cells from the inside surface of the cheek). The procedures used for prenatal testing carry a small but real risk of losing the pregnancy (miscarriage) because they require a sample of amniotic fluid or tissue from around the fetus. Many of the risks associated with genetic testing involve the emotional, social, or financial consequences of the test results. People may feel angry, depressed, anxious, or guilty about their results. The potential negative impact of genetic testing has led to an increasing recognition of a "right not to know".<ref>Roberto Andorno, "The right not to know: an autonomy-based approach", ''Journal of Medical Ethics,'' 2004, 30(5): 435–439 [http://uzh.academia.edu/RobertoAndorno/Papers/446836/The_right_not_to_know_an_autonomy-based_approach]</ref> In some cases, genetic testing creates tension within a family because the results can reveal information about other family members in addition to the person who is tested. The possibility of [[genetic discrimination]] in employment or insurance is also a concern. Some individuals avoid genetic testing out of fear it will affect their ability to purchase insurance or find a job.<ref>Amy Harmon, [http://www.nytimes.com/2008/02/24/health/24dna.html?_r=2&scp=5&sq=Genetic&st=nyt&oref=slogin&oref=slogin "Insurance Fears Lead Many to Shun DNA Tests,"] [[The New York Times]], February 24, 2008</ref> Health insurers do not currently require applicants for coverage to undergo genetic testing, and when insurers encounter genetic information, it is subject to the same confidentiality protections as any other sensitive health information.<ref>[http://www.actuary.org/pdf/health/geneticmono.pdf "Genetic Information and Medical Expense Insurance"], [[American Academy of Actuaries]], June 2000</ref> In the United States, the use of genetic information is governed by the [[Genetic Information Nondiscrimination Act]] (GINA) (see discussion below in the section on government regulation). Genetic testing can provide only limited information about an inherited condition. The test often can't determine if a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time. Another major limitation is the lack of treatment strategies for many genetic disorders once they are diagnosed. A genetics professional can explain in detail the benefits, risks, and limitations of a particular test. It is important that any person who is considering genetic testing understand and weigh these factors before making a decision. ==Direct-to-Consumer genetic testing== Direct-to-Consumer (DTC) genetic testing is a type of genetic test that is accessible directly to the consumer without having to go through a health care professional. Usually, to obtain a genetic test, health care professionals such as doctors acquire the permission of the patient and order the desired test. DTC genetic tests, however, allow consumers to bypass this process and order one themselves. There are a variety of DTC tests, ranging from testing for breast cancer alleles to mutations linked to cystic fibrosis. Benefits of DTC testing are the accessibility of tests to consumers, promotion of proactive healthcare and the privacy of genetic information. Possible additional risks of DTC testing are the lack of governmental regulation and the potential misinterpretation of genetic information. ===Controversy=== DTC genetic testing has been controversial due to outspoken opposition within the scientific community. Critics of DTC testing argue against the risks involved, the unregulated advertising and marketing claims, and the overall lack of governmental oversight.<ref>Hunter et al., [http://content.nejm.org/cgi/content/full/358/2/105 "Letting the Genome out of the Bottle"] New England Journal of Medicine</ref> 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 severe misreading of test results. Without professional guidance, consumers can potentially misinterpret genetic information, causing them to be deluded about their personal health. Some advertising for direct-to-consumer genetic testing has been criticized as conveying an exaggerated and inaccurate message about the connection between genetic information and disease risk, utilizing emotions as a selling factor. An advertisement for a BRCA-predictive genetic test for breast cancer stated: “There is no stronger antidote for fear than information.”<ref>Gollust et al., [http://jama.ama-assn.org/cgi/content/full/288/14/1762#REF-JSC20258-14 "Limitations of Direct-to-Consumer Advertising for Clinical Genetic Testing,"] JAMA.2002; 288: 1762-1767</ref> ==Government regulation in the United States== {{Globalize/US|date=April 2011}} Currently, the U.S. has no strong Federal regulation moderating the DTC market. Though there are several hundred tests available, only a handful are approved by the Food and Drug Administration (FDA); these are sold as at-home test kits, and are therefore considered "medical devices" over which the FDA may assert jurisdiction. Other types of DTC tests require customers to mail in DNA samples for testing; it is difficult for the FDA to exercise jurisdiction over these types of tests, because the actual testing is completed in the laboratories of providers. As of 2007, the FDA had not yet officially substantiated with scientific evidence the claimed accuracy of the majority of direct-to-consumer genetic tests.<ref>Shawna Williams and Gail Javitt, [http://www.dnapolicy.org/policy.issue.php?action=detail&issuebrief_id=32 "Direct-to-consumer genetic testing: empowering or endangering the public?,"] The Genetics and Public Policy Center, July 25, 2006 (updated 6/15/2007)</ref> With regard to genetic testing and information in general, legislation in the [[United States]] called the [[Genetic Information Nondiscrimination Act]] prohibits group health plans and health insurers from denying coverage to a healthy individual or charging that person higher premiums based solely on a [[genetic predisposition]] to developing a disease in the future. The legislation also bars employers from using individuals’ genetic information when making [[hiring]], [[firing]], job placement, or [[Promotion (rank)|promotion]] decisions.<ref name="OMB support">[http://www.genome.gov/Pages/PolicyEthics/GeneticDiscrimination/SAPonHR493.pdf Statement of Administration policy], Executive Office of the President, Office of Management and Budget, 27 April 2007</ref> The legislation, the first of its kind in the U.S.,<ref name="tedkennedy">[http://kennedy.senate.gov/newsroom/press_release.cfm?id=4FCF8E86-4706-4E74-B451-36253C5A425D Kennedy in support of genetic information nondiscrimination bill], Abril 24, 2008. Last access: 28/05/2008.</ref> was passed by the [[United States Senate]] on April 24, 2008, on a vote of 95-0, and was signed into law by President [[George W. Bush]] on May 21, 2008.<ref name="Law">{{cite news | url=http://blog.wired.com/wiredscience/2008/05/the-genetic-inf.html | title=Genetic Discrimination by Insurers, Employers Becomes a Crime | author=Keim, Brandon | work=Wired.com | date=May 21, 2008 | accessdate=2008-05-28}}</ref><ref>[http://www.kaisernetwork.org/daily_reports/rep_index.cfm?DR_ID=52305 "Administration News | President Bush Signs Genetic Nondiscrimination Legislation Into Law,"] Kaiser Daily Health Policy Report, [[Kaiser Family Foundation]], May 22, 2008</ref> It went into effect on November 21, 2009. == In popular culture == Some possible future ethical problems of genetic testing were considered in the [[science fiction film]] ''[[Gattaca]]'', the novel [[Next (novel)|''Next'']], and the science fiction [[anime]] series "[[Gundam Seed]]". Also some films which include the topic of genetic testing include ''[[The Island (2005 film)|The Island]]'', ''[[Halloween: The Curse of Michael Myers]]'', and the ''[[Resident Evil (film)|Resident Evil]]'' series. == See also == {{Portal|Molecular Anthropology}} * [[Personalized medicine]] * [[Eugenics]] * [[Full Genome Sequencing]] * [[Gene Diagnostics]] * [[Gene theft]] * [[Genetic counseling]] * [[List of genetic disorders]] *[[List of genetic genealogy topics]] * [[List of human genes]] * [[Misattributed paternity]] == References == {{Reflist}} ==Further reading== *{{cite book|author=Anne Hart|title=The Beginner's Guide to Interpreting Ethnic DNA Origins for Family History: How Ashkenazi, Sephardi, Mizrahi & Europeans Are Related to Everyone Else|url=http://books.google.com/books?id=DHBuRpLQaKQC&pg=PP1|date=July 2003|publisher=iUniverse|isbn=978-0-595-28306-4}} == External links == * [http://www.genetests.org GeneTests] US [[National Institutes of Health]] funded resource on genetic testing. * [http://www.eurogentest.org EuroGentest] European network for test development, harmonization, validation and standardization. * [http://www.techgene.eu TECHGENE] European project on genetic testing and next generation sequencing technology. * [http://www.genomind.com Genomind] American corporation specializing in neuropsychiatric genetic testing. * [http://www.23andme.com/ 23andme] American corporation specializing in DTC genetic testing. * [http://oba.od.nih.gov/gtr/gtr.html Genetic Testing Registry] NIH information resource on genetic testing. * [http://www.dnatest.org/genetic/ DNATest.org] Resource about genetic testing. * [http://www.genetic-testing-forum.com Genetic Testing Forum] Crowd sourced information and discussion on genetic testing. * Downloadable article: "Evidence that a West-East admixed population lived in the Tarim Basin as early as the early Bronze Age" Li et al. ''BMC Biology'' 2010, 8:15. {{cite web|url=http://www.biomedcentral.com/content/pdf/1741-7007-8-15.pdf |title=Evidence that a West-East admixed population lived in the Tarim Basin as early as the early Bronze Age |format=PDF |date= |accessdate=2011-06-07}} * [http://www.knowyourgenes.org KnowYourGenes.org] Genetic Disease Foundation * [http://www.geneticalliance.org/issues.testing Genetic Alliance] {{DEFAULTSORT:Genetic Testing}} [[Category:Medical tests]] [[Category:Medical ethics]] [[Category:Medical genetics]] [[Category:Alternatives to animal testing]] [[da:Gentest]] [[es:Examen genético]] [[fr:Analyse génétique]] [[he:בדיקות סקר גנטיות]] [[nl:Genetische screening]] [[ja:遺伝学的スクリーニング]] [[sv:Gendiagnostik]] [[zh:基因檢測]]'