Genetic Screening: Types of Tests and Applications

hereditary Screening Types of Tests and Applications heritable SCREENINGAOUDUMBARI B.DESAIWhat is Genetic Screening?Genetic covert is a ferment in which DNA is running played to snap if a soul has every communicable indicators of diseases. It stern too be defined as an investigateal proficiency employ for identification and selection of person who possess phenotype of our fire in a mutangenized population. Thus contractable back squirt withal be called as phenotypic screening. It helps us to provide a stop insight of function of component in an individual. It has got applications in various genome project. The functioning of cistron underside be well determined by foregoing ancestral screen or Reverse transmissible screen. Forward ancestral screening first approaches towards the phenotype and then moves towards stationing genes i.e, genes responsible for a differentiateicular phenotype in an individual is identified. Whereas in reverse genetic screen it s tarts with gene or set of genes and moves towards analyzing the resultant phenotype by assaying its effect of disruption. A defined genetic background of organism being used and constant experimental enumerate for identification of mutations of interest be the two key component of favored forward genetic screening. Define genetic background helps to identify and fall affected genes in mutant individual with greater efficiency (Herman .R.K, et al.,2005). umpteen an(prenominal) a times genetic screening and genetic attempting be considered to be a common terms, however there is difference betwixt genetic screening and trying. Genetic screening is a technique in which set of diagnostics test atomic number 18 used on pear-shaped number of individuals to test these individuals who are at high risk of genetic unsoundnesss and are the carriers of that specific genes, whereas genetic testing uses different laboratory test to identify the genetic status of individual. The ind ividuals who are already suspected to be at a higher risks for a position genetic disorder undergo the genetic testing. It is based on medical history of family or on screening tests. But the similarity amid both the test is both of them undergo laboratory tests to identify the presence of specific genes which may cause genetic disorders.Genetic screening is a term that is to a fault encountered in prenatal screening with pregnant women. Many looker do screening on a broad spectrum in large number of great deal to bring potential for genetic diseases. Nowadays genetic screening is also used by wellness insurance companies to screen the people for genetic disorders and avoid paying extra money. Genetic screening also include new born(p) genetic screening to identify new born who would benefit from early treatment. Reproductive genetic screening is also through with(p) to help reproductive decision making, and in this family history of the patient is checkered to identify ind ividuals who would get added benefit from additional prevention measure.Types of screening renewingThere are different screening variations which are used to identify genes that cause a mutants in phenotype of interest. Some of them are as follows hydrofoilEnhancer screening is used to screen an mutant individual with cognise genetic mutation. It can further be used to screen an individual with additional gene mutations that has its major role in biological and physiological processes. It is the mutation in one genes that causes the intensification of phenotype resulted due to mutation in some new(prenominal) gene. The genetic enhancer screening identifies a mutations which enhance aphenotype of interest in already mutant individual.Source http//www.wormbook.org/chapters/www_geneticenhancers/geneticenhancers.html Synthetic interaction betweenmec-8andsym-3.(A) Themec-8 sym-3double mutant has a highly penetrant defect the preceding tip (arrow) of the pharynx is not right joine d to the anterior tip of the body (arrowhead), and a functional spill the beans is not formedThe mutants also shed a bulbous nose, an enlargement of the anterior-most part of the body, which is particularly evident in the example shown here. The junction of the pharynx and anterior end of the body is normal in thesym-3single mutant (B) and in themec-8single mutant (C).SuppresorIt is used to identify the suppressor mutations. Suppressor mutations revert the original mutations. It can be defined as the one which suppresses the phenotype of original mutations and are the some some early(a) mutations on the site of chromosome which are distinct from the mutation under study. It has an intragenic downsizing and extragenic suppression. Intragenic suppression is the one in which mutation is in same gene as in original mutation.whereas if there is a mutation in different gene then it is called as extragenic suppression or intergenic suppression.Temperature unsandedIt is a type of scr eening technique which involves performing temperature shifts to enhance a mutant shift. The organism grown at a lower temperature willing have normal phenotype whereas at higher temperature the mutation in that particular gene will make it unstable. For example Lee Hartwell and Paul nurture independently carried come forth temperature sensitive screening to identify mutants defective in cell cycle S.cerevisiae and S.pombe.Types of Genetic Screening Presymptomatic screening aircraft carrier screeningparental screening,newborn screening,carrier screening,forensic screening and readiness screening.Presymptomatic screening is used to screen the patients whose health is in danger. immune carrier screening is used to carry out the analysis of individuals with a gene or a chromosome abnormality that may cause problems either for outcome or the person screened.it is carried out in healthy individuals where there can be a risk of genes harmful to offsprings or future generation. This ca n be done by testing of blood or waver paper samples and can show the presence of a particular genetic trait, changes in chromosomes, or changes in DNA that are associated with inherited diseases in well individuals. For example carrier screening is done for sickle cell anaemia, infantile amaurotic idiocy disease, duchenne muscular dystrophy, haemophilia, Huntingtons disease, and neurofibromatosis.Prenatal screening is carried out in a foetus when it is at risk for various identifiable genetic diseases or traits. It began in 1966.Newborn screening is related with the analysis of blood or weave samples taken in early infancy in order to honour genetic diseases for which early intervention can avert serious health problems or death. Newborn screening was started in 1960 with the ability to test newborns for a rare metabolic disease, phenylketonuria (PKU). Two other examples of newborn screening are the testing of African American infants for sickle cell anemia and Ashkenazic J ews for Tay-Sachs disease.Forensic screening is used in criminal investigations it is used to to discover a genetic linkage between suspects and evidence discovered in criminal investigations. As DNA of each and every person is unique, many people are reluctant to see such development become part of any national database, which might include info not only round identity but also about proclivity toward disease or behavior.Susceptibility screening is a technique which is used to screen a selected population for genetic susceptibility to environmental hazards. It helps in the identification of workers who may be susceptible to toxic substances that are found in their workplace and may cause future disabilities.Types and Uses of Genetic TestsSource - Norrgard.K., 2008http//www.nature.com/scitable/topicpage/medical-careers-genetic-screening-and-diagnostics-639Purpose of genetic screeningGenetic screening acts as an important tool in modern preventive medicine.It is used to keep up the diagnosing in patients with symptoms.Genetic screening also helps to advise other family members of the diagnosed patient to detect whether they also have the disease or have genetic markers for the disease even if they dont have symptoms ,and also to check whether they are carriers or are neither.It also helps in detecting when one assistant is a sufferer or carrier, to test the other confederate in order to advise whether their child will have the disease, be a carrier or will not have the disease.If diseases observed in both the parents, the child must inherit the disease or the genetic markers for the disease. It may happen that one parent has the disease and the other partner also has the genetic markers for it but there are no symptoms for it, because the child may develop the disease or alternatively may not show any symptoms during its lifetime. If one parent has the disease and the other is a carrier, in each pregnancy there is a 5050 chance of the child inheriting the disease.In the population, screening is carried out to discover undiagnosed sufferers or those with genetic markers for the disease, to discover carriers and to aid research into the prevalence and severity of the disease and the carrier ratio.Maternal serum alpha-fetoprotein (MSAFP) screening, deepen MSAFP, amniopennyesis, chorionic villus sampling (CVS), percutaneous umbilical blood sampling (PUBS),fetal biopsy and fetal cell sorting are some of the genetic screening tests which are currently available for pregnant women. MSAFP is a blood-screening test. It is performed at the 16-18 week motherliness date and it tests for spina bifida. Enhanced MSAFP is also a similar type of blood-screening test that measures levels of certain biochemical markers to test for the presence of Downs syndrome. But the only occasion is that this test only has an accuracy of 60-65%. amnio is performed at the 16-18 week of gestation. Amniocentesis uses amniotic fluid to test for chromosomal abn ormalities. It is also used to find biochemical abnormalities at the genetic level, it helps in detecting up to clxxx genetic disorders. CVS i.e, chorionic villus sampling screening is performed at 10-12 weeks into gestation and it uses chorion tissue for chromosomal analysis in biochemical and DNA studies. It is not wide used because this test has a drawback of correlation to produce newborns with limb abnormalities. ).Percutaneous umbilical blood sampling, PUBS is performed later on week 18 . PUBS is used only as a confirmation test based on results from previous other tests. In fetal tissues are taken for DNA testing . fetal cell sorting includes an experimental procedure in whcich blood is taken from mother and fetal cells are tested in mothers blood.Oberle,I. D. Camerino.G, 1985 carried out genetic screening for hemophilia A(classic hemophilia) with polymorphic DNA probe. They collected blood samples after informed consent from13 families and carried out coagulation and immun ologic assay. In this experiment they develop a new technique to screen the patients for hemophiliaA in the families at risk for the disease. A DNA probe (St14) that detects a very polymorphic region on the human X chromosome has been shown to be closely colligate to hemophilia A. They observed that there was no recombination between the St14 locus and hemophilia A in 12 families studied. The odds in favor of linkage are 4.4 x 109to 1 (lod score, 9.65). They found that there was 0 to 6.5% chance of the 95 per cent confidence interval of a recombination between St14 and hemophilia A. This informative DNA probe which causes families in risk of hemophilia A in more than 90 per cent, can be used in conjunction with classic biologic assays to identify carriers with an accuracy of 96 per cent or more. If a small risk of misclassification due to crossover between the test and the disease loci is accepted, this DNA marker should allow first-trimester prenatal diagnosis of hemophilia A. S egregation analysis with St14 may thus represent a major improvement in genetic counseling for hemophilia A. mixer dilemmas of genetic screeningThough genetic screening is beneficial to hostelry it has a got lot of controversies because by using genetic marker to check for genetic disorders is definitely beneficial to society because due to early diagnosis a preventive symptom treatment can be effrontery by early medical assisantnce but however many a times it is observed that if a genetic disorder is detected in fetus then fetus is readily aborted. So here a controversy comes because no one has got right to end anyones life. Also many a times it happens that individuals carrying a genetic disorder or diseases are being discriminated by society or by health insurers and employers. thereof this genetic screening has brought up a new legal, social and honourable dilemmas.ReferencesKarthikeyan. M.1999, Human Genetic Screening, http//www.ndsu.edu/pubweb/mcclean/plsc431/students99/kar thikeyan.htmNorrgard.K., 2008, Medical Careers Genetic Screening and Diagnostics, Nature Education1(1) pg no- 92http//www.nature.com/scitable/topicpage/medical-careers-genetic-screening-and-diagnostics-639Burke.W., et al., 2011, Genetic Screening , Epidemologic reviews Oxford journal 33(1) pg no- 148164http//www.ncbi.nlm.nih.gov/pmc/articles/PMC3166195