Editing Genetic testing (section)

===Diagnostic testing===
* [[Cell-free fetal DNA]] (cffDNA) testing{{snd}} a non-invasive (for the fetus) test. It is performed on a sample of venous blood from the mother, and can provide information about the fetus early in pregnancy.<ref>{{cite journal | vauthors = Van den Veyver IB | title = Recent advances in prenatal genetic screening and testing | journal = F1000Research | volume = 5 | pages = 2591 | date = 28 October 2016 | pmid = 27853526 | pmc = 5089140 | doi = 10.12688/f1000research.9215.1 | doi-access = free }}</ref> {{As of|2015}} it is the most sensitive and specific screening test for [[Down syndrome]].<ref name="BMO15">{{cite book| vauthors = Permezel M, Walker S, Kyprianou K |title=Beischer & MacKay's Obstetrics, Gynaecology and the Newborn|date=2015|publisher=Elsevier Health Sciences|isbn=9780729584050|page=74|url=https://books.google.com/books?id=eR9uDQAAQBAJ&pg=PA74|access-date=24 January 2017|language=en}}</ref>
* [[File:Phenylketonuria testing.jpg|thumb|Newborn heel-prick blood sample collection]] [[Newborn screening]]{{snd}} used just after birth to identify genetic disorders that can be treated early in life. A blood sample is collected with a heel prick from the newborn 24–48 hours after birth and sent to the lab for analysis. In the United States, newborn screening procedure varies state by state, but all states by law test for at least 21 disorders. If abnormal results are obtained, it does not necessarily mean the child has the disorder. Diagnostic tests must follow the initial screening to confirm the disease.<ref name="Newborn Screening">{{cite web| work = Genetics Home Reference | location = Bethesda (MD) | publisher = National Library of Medicine (US) |title=Newborn Screening|url=https://medlineplus.gov/newbornscreening.html|access-date=2015-03-22}}</ref> 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]] (PKU, a genetic disorder that causes [[mental illness]] if left untreated) and [[congenital]] [[hypothyroidism]] (a disorder of the [[thyroid]] gland). People with PKU do not have an enzyme needed to process the amino acid phenylalanine, which is responsible for normal growth in children and normal protein use throughout their lifetime. If there is a buildup of too much phenylalanine, brain tissue can be damaged, causing developmental delay. Newborn screening can detect the presence of PKU, allowing children to be placed on special diets to avoid the effects of the disorder.<ref name="Newborn Screening" />
* [[Diagnostic testing]]{{snd}} 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. For example, people with a family history of polycystic kidney disease (PKD) who experience pain or tenderness in their abdomen, blood in their urine, frequent urination, pain in the sides, a urinary tract infection or kidney stones may decide to have their genes tested and the result could confirm the diagnosis of PKD.<ref>{{cite web|last1=Mayo Clinic Staff|title=Polycystic Kidney Disease|url=http://www.mayoclinic.org/diseases-conditions/polycystic-kidney-disease/basics/symptoms/con-20028831|website=Mayo Clinic|publisher=Mayo Foundation for Medical Education and Research|access-date=18 November 2016}}</ref> Despite the several implications of genetic testing in conditions such as epilepsy or neurodevelopmental disorders, many patients (specially adults) do not have access to these modern diagnostic approaches, showing a relevant diagnostic gap.<ref>{{cite journal | vauthors = Aledo-Serrano A, García-Morales I, Toledano R, Jiménez-Huete A, Parejo B, Anciones C, Mingorance A, Ramos P, Gil-Nagel A | title = Diagnostic gap in genetic epilepsies: A matter of age | journal = Epilepsy & Behavior | volume = 111 | pages = 107266 | date = October 2020 | pmid = 32610249 | doi = 10.1016/j.yebeh.2020.107266 | s2cid = 220128591 }}</ref>
* [[Carrier testing]]{{snd}} 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 like [[cystic fibrosis]].
* [[Preimplantation genetic diagnosis]]{{snd}} performed on [[human embryo]]s prior to the implantation as part of an [[in vitro fertilization]] procedure. Pre-implantation testing is used when individuals try to conceive a child through in vitro fertilization. Eggs from the woman and sperm from the man are removed and fertilized outside the body to create multiple embryos. The embryos are individually screened for abnormalities, and the ones without abnormalities are implanted in the uterus.<ref>{{cite web|last1=Mayo Clinic Staff|title=Genetic testing Why it's done - Tests and Procedures - Mayo Clinic|url=http://www.mayoclinic.org/tests-procedures/genetic-testing/basics/why-its-done/prc-20014802|website=Mayo Clinic|access-date=2015-01-22}}</ref>
* [[File:ChorionicVillus.png|thumb|Small amounts of the chorionic villi are sampled during CVS]] [[Prenatal diagnosis]]{{snd}} 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. One method of performing a prenatal genetic test involves an [[amniocentesis]], which removes a sample of fluid from the mother's amniotic sac 15 to 20 or more weeks into pregnancy. The fluid is then tested for chromosomal abnormalities such as Down syndrome (trisomy 21) and trisomy 18, which can result in neonatal or fetal death. Test results can be retrieved within 7–14 days after the test is done. This method is 99.4% accurate at detecting and diagnosing fetal chromosome abnormalities. There is a slight risk of miscarriage with this test, about 1:400. Another method of prenatal testing is [[chorionic villus sampling]] (CVS). Chorionic villi are projections from the placenta that carry the same genetic makeup as the baby. During this method of prenatal testing, a sample of chorionic villi is removed from the placenta to be tested. This test is performed 10–13 weeks into pregnancy and results are ready 7–14 days after the test was done.<ref>{{cite web| vauthors = Haugen JA |title=The Facts on Prenatal Testing |url=http://www.haugenobgyn.com/prenatal_testing.aspx |website=John A. Haugen Associates Obstetrics and Gynecology |access-date=2015-03-26 |url-status=dead |archive-url=https://web.archive.org/web/20150402123732/http://www.haugenobgyn.com/prenatal_testing.aspx |archive-date=2015-04-02 }}</ref> Another test using blood taken from the fetal umbilical cord is [[percutaneous umbilical cord blood sampling]].
* Predictive and presymptomatic testing{{snd}} 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>{{cite journal | vauthors = Antoniou A, Pharoah PD, Narod S, Risch HA, Eyfjord JE, Hopper JL, Loman N, Olsson H, Johannsson O, Borg A, Pasini B, Radice P, Manoukian S, Eccles DM, Tang N, Olah E, Anton-Culver H, Warner E, Lubinski J, Gronwald J, Gorski B, Tulinius H, Thorlacius S, Eerola H, Nevanlinna H, Syrjäkoski K, Kallioniemi OP, Thompson D, Evans C, Peto J, Lalloo F, Evans DG, Easton DF | title = Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case Series unselected for family history: a combined analysis of 22 studies | journal = American Journal of Human Genetics | volume = 72 | issue = 5 | pages = 1117–1130 | date = May 2003 | pmid = 12677558 | pmc = 1180265 | doi = 10.1086/375033 }}</ref> Hereditary breast cancer along with ovarian cancer syndrome are caused by gene alterations in the genes BRCA1 and BRCA2. Major cancer types related to mutations in these genes are female breast cancer, ovarian, prostate, pancreatic, and male breast cancer.<ref name="National Institute of Health">{{cite web|title=Genetic Testing for Hereditary Cancer Syndromes|url=http://www.cancer.gov/cancertopics/genetics/genetic-testing-fact-sheet|website=National Cancer Institute|publisher=National Institute of Health|access-date=18 November 2016|date=2013-04-22}}</ref> Li-Fraumeni syndrome is caused by a gene alteration on the gene TP53. Cancer types associated with a mutation on this gene include breast cancer, soft tissue sarcoma, osteosarcoma (bone cancer), leukemia and brain tumors. In the Cowden syndrome there is a mutation on the PTEN gene, causing potential breast, thyroid or endometrial cancer.<ref name="National Institute of Health" /> 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, help with making decisions about medical care and provide a better prognosis.
* [[Pharmacogenomics]]{{snd}} determines the influence of genetic variation on drug response. When a person has a disease or health condition, pharmacogenomics can examine an individual's genetic makeup to determine what medicine and what dosage would be the safest and most beneficial to the patient. In the human population, there are approximately 11 million single nucleotide polymorphisms (SNPs) in people's genomes, making them the most common variations in the human genome. SNPs reveal information about an individual's response to certain drugs. This type of genetic testing can be used for cancer patients undergoing chemotherapy.<ref>{{cite web|title=Genetic Testing|url=http://www.ama-assn.org/ama/pub/physician-resources/medical-science/genetics-molecular-medicine/related-policy-topics/genetic-testing.page?|website=American Medical Association|access-date=2015-01-23}}</ref> A sample of the cancer tissue can be sent in for genetic analysis by a specialized lab. After analysis, information retrieved can identify mutations in the tumor which can be used to determine the best treatment option.<ref>{{cite web|url=http://www.cancercenter.com/cancer-genomics/genomic-tumor-assessment/|title=Genomic Tumor Assessment|website=Cancer Treatment Centers for America|publisher=Rising Tide|access-date=18 November 2016|archive-date=19 November 2016|archive-url=https://web.archive.org/web/20161119181930/http://www.cancercenter.com/cancer-genomics/genomic-tumor-assessment/|url-status=dead}}</ref>