Clinical in genetic analysis and the basic applications
G enetik tests in clinical practice all over the world are becoming more widespread and integrated in many areas. As of today the most common of these applications are mainly as follows:
1) diagnostic tests ,
2) Predictive tests ,
3) carrier testing ,
4) prenatal screening tests ,
5) embryo screening tests (emplementasyon pre-screening) ,
6) the newborn screening tests ,
7) Relationship and histocompatibility testing ,
8) genotyping ,
9) stem cell and / or DNA banking .
Diagnostic genetic tests are still being treated who are symptomatic or who have one person concerned about a genetic disorder in the primary or secondary to rule out or confirm the incelemelerdir. Diagnostic genetic tests can be applied to individuals of all ages and both are usually less risky than other alternative test methods, and is cheap and gives more accurate results. After all, the patient is a genetic disorder in the shape of the detection and treatment will change the course of the disease in favor of the patient and the physician. Moreover, these diagnostic and patient and family better understand the current situation and the nature of reference for the future will carry a gain in realistic decisions. However, in some cases, genetic tests in the diagnosis of the disease is not the first resort or the method, this method, multiple testing may be required for definitive conclusion should be taken into account.
Predictive genetic tests, family history or risk factors for a possible genetic disorder with clinical findings at the border, but the applications are still individuals who are asymptomatic. The presence of a positive test result, however, that unutulmamladır detected by the type of genetic abnormality or diagnosis of a disease presemptomatik or only a predisposing factor detection means. For example, a test result in the detection of a mutation in line with Huntington's disease, Huntington's disease, the diagnosis means presemptomatik PERSON. In other words, if these patients live long enough to start to give symptoms of Huntington's disease is an unavoidable fact. On the other hand, the nature of a risk factor for breast cancer patients, detection of a mutation in this patient indicates the presence of only a predisposing risk factor. When the formation of breast cancer in this patient is not certain though probable. If you need to make a rough generalization, multi-factorial reasons, emerging diseases, or the accumulation of multiple genetic mutations in individuals tested positive predictive test result means that the tendency of this disease is not diagnosed with the disease. This group of patients who would benefit from a maximum of people, such as risk factor modification in preventive medicine creates a personalized and effective alternative method of predictive genetic analysis of any irreplaceable location.
Predictive genetic analysis ( PGA ), early diagnosis and treatment is medically known to affect morbidity and mortality in medically indicated in all cases and especially in the secondary age group. What is more predictive of genetic analysis, and the patient followed the doctor, as well as individual health goals for the future for himself and the most appropriate patient follow-up strategy that led to the detection of a unique tool.
Difficult to analyze the results of the acceptance of some predictive genetic test can affect the eyes of individuals to life, the patient may lead to severe psychosocial complications. In such events to minimize the need to adhere to three basic principles of genetic testing centers that are: First, the person giving the sample, the test polyclinical a detailed and clearly written with the signature of the person without a permit under any circumstances should not be considered for sample predictive analysis. Second, under certain circumstances, which is symptomatic of a person close to predictive genetic testing in order to analyze the disease-specific mutation is identified, or the patient's family, such as correlation tests have shown the existence of this disease should be sought Prerequisites. Finally, remember that if you are already known to be diagnosed of the disease or treatment of any medical intervention for the benefit of patients have no means to reach this diagnosis will be very limited. Therefore, in asymptomatic individuals in the United States for the treatment of children and adult diseases are not diseases that may occur at an early age to test for the predictive ASHG ( The American Society of Human Genetics ), as prohibited in principle by the ethics committees.
Carrier testing is an autosomal recessive genetic structure of individuals, or X-linked genetic switch kromozumuna that carry the disease-causing genetic mutations in the tests carried out to investigate. As is known, this type of carrier of genetic abnormalities usually do not cause any symptoms. However, in cases of consanguineous marriages, especially in certain ethnic groups or families with a history of such a disease, and more couples to have children who think the actual detection of reproductive risk factors, but genetic testing is possible with the carrier.
Carrier testing of a baby yet to be born with serious genetic disorders of pregnancy that occur can be prevented or unnecessary fears, worries can be eliminated duplicates. The main goal of healthy families, decisions about having children but the youngster, the carrier of genetic tests, the emergence of family members to apply in order to prevent possible personal injury or social services to families, genetic counseling and education must be ide.
However, it should be noted that the same gene, particularly as a result of many different mutations can occur only in some cases, a single screening of all of these possibilities does not make sense in many ways. In such cases, the carrier-specific test method should be preferred to the patient before the family member was to perform diagnostic tests. In addition, sometimes the ideal carrier testing in terms of both cost and efficiency, not direct tests of biochemical tests (eg enzyme activity) may be.
Prenatal screening tests performed to evaluate the approach using the health status of a fetus during pregnancy. Routine prenatal screening tests may be done within the scope (for example, triple test), family history, ethnic, or environmental risk factors, such as poor obstetric history or advanced maternal age increases the risk of carrying the baby for a genetic disorder known as the reference test in all cases in the last resort may be asked to confirm the diagnosis.
Routine fetal ultrasound scans, as well as non-invasive maternal blood alpha-fetoprotein (AFP), chorionic gonadotropin (hCG) and free estriol (UE3) to looking after the triple test ( Multiple marker screening ) should be preferred. However, in cases where genetic analysis indicated the test material should be fetüsten invasive way: an early amniocentesis or chorionic villus sampling in fetuses under 15 weeks (CVS) and, in fetuses older than 12 weeks of the amniocentesis (20 weeks), placental biopsy, cordocentesis (PUBS) or with fetoskopi fetal skin biopsy material suitable for genetic analysis done may be obtained. After all, the supply of material prior to invasive prenatal genetic analysis of ways to do this supplies the center with the center contact with the sample should be adopted and planned in a coordinated manner.
All invasive fetal interventions and / or to the mother of a separate risk should not be forgotten carried. For this reason, prenatal genetic analysis indicated this issue would be permitted to be taken and analyzed after the spouses must be present in the genetic counseling service (for example , carrier testing after ) should not be forgotten. Again, as stated earlier, if possible, before some of prenatal screening tests, patients' family history family member samples to be taken d to be a diagnostic genetic testing and pre-determination of the mutation to be scanned both in an attempt to avoid unnecessary invasive to the fetus is a sure way to be elected.
After all, the prenatal screening tests in the diagnosis of genetic diseases that may arise in adulthood, in other words not suitable for predictive purposes use of the code of ethics. In such cases, to be evaluated again after the birth of the child's family or a genetic counselor should be directed to çağırılmalı
Embryo screening tests ( PGD Preimplantation Genetic Diagnosis = ), in vitro fertilization ( IVF ) [T- up-doll ] method before leaving the womb of mother-to embryos created with the specific genetic mutations or abnormalities in terms of possible genetic tests used for screening. Usually, these tests are at high risk of having children is a serious genetic abnormality (such as a high risk of penetration of a genetic disease is present in brother and sister were born earlier), families can be recommended as an alternative to prenatal screening.
However, the high cost, limited range of applications and services of sufficient quality, the number of centers that could be very few reasons not very popular in this application. Because these tests that increase costs and create ethical problems for the first factor of the application be successful, a sufficient number of separate embryos, distinct need for testing and for this reason that the number of embryos available for implantation, which is already a small decrease of drop down chances of capturing a successful pregnancy. Therefore, unless there is a valid reason many families instead of embryo screening should be offered prenatal diagnostic tests.
Note : It is a valid medical reason for gender identification of embryos without the screening test (or prenatal testing) is clearly not ethical and is prohibited by the Ministry of Health of Turkey.
Newborn screening tests for early detection of morbidity or mortality can be lessened by the way, and that the availability of certain medical interventions for genetic diseases in order to capture the approach using a high-risk infants. Population studies indicate that the risks, some of which vary according to each new born newborn screening tests done in many countries and different states of the United States of America are required by law. This type of mandatory (or routine) tests immediately unless otherwise instructed in writing the birth parents should be applied subsequently.
Newborn screening tests for diagnosis of a disease, not requiring further investigation or the genetic analysis are made in order to identify individuals. Routine practice, especially in the family, unless she wants, what are the screening tests, or if they have negative test results may not be reported to families. For this reason, the test results of additional tests, when a written request, and if so, which makes the test center with the submitted sample. However, false-positive screening test results and family history of understanding or abstraction does not cause unnecessary concern for the parents must be informed about the subject before giving birth.
Kinship and conformance testing of tissue contrast to other genetic tests in order to determine a genetic predisposition to the disorder or disease is not diagnosed, the genetic similarity between different individuals or tests conducted to determine the differences. Common aspect of these tests is more than one sample (eg, child and alleged father, and person) at the same time they are subjected to analysis of the similarity or difference between the genetic structure of the report is to be compared. Therefore, analysis of the genetic material within the kinship tests often associated with a disease-causing genes or fragments of any disease, but often in healthy individuals in the genetic structure indicative of DNA regions known to differ. Structural variations and the variations in the incidence rates of the tested individuals, including the ethnic group known to the examination of a sufficient number of DNA between the parties, no way out of a possible genetic link genetic analysis to reach a precision that can not be displayed.
Maternity-paternity and zygosity testing is usually the reasons for the application of social nedenlerledir. However, in rare cases, some of these types of tests made on the basis of family genetic analysis may become necessary for the correct interpretation, or be affirmed. If the test is made legal reasons, to report the testing process and a special sensitivity and confidentiality is a prerequisite. Kinship legal reasons, the interpretation of tests, but that there is no certainty that a child can be compared to the person's biological children should not be forgotten. The counter-proof supply of a limited number of cared for by the analysis of genetic region is not possible.
Zygosity testing for medical indications leading to serious genetic diseases, the brothers was to determine the risk of the disease tendency. They are in separate chorionic sacs of fetuses with prenatal zygosity tests but genetic testing is indicated for edilebiliyorsa documented. It should be remembered that if the twins is in the chorionic sac, although their possible physical differences (for example, one larger than the other, and appear healthy) twins are monozygotic twins that genetic testing is not required. Postnatal zygosity tests the brothers from another medical indication in terms of potential organ or tissue transplant tespitindedir genetic proximity.
Kinship and genetic tests based on the histocompatibility testing such as comparisons of statistical analysis, the sensitivity of the test subject as the number of loci and the cost will increase correspondingly. In addition, the implementation of prenatal testing, or other factors that increase the cost of the increase in the number of individuals tested. This type of genetic analysis is usually done directly, without a medical indication, usually social or financial aspects of individual health coverage under the applicable tests should also be noted.
Genotyping of individuals to be characterized in terms of genetic structure and genetic predisposition to disease is a medical test as a multi-factorial structure to be categorized according to the type of genetic analysis applied to an individual. The goal of genetic regions that cause disease or illness directly related to the existence of fragments, including the ethnic group of individuals as a statistical risk factor for certain diseases in the affected (increase or decrease) known SNPs ( single nucleotide polymorphism ) analysis of the motives of some genetic variations such as. Typically, this analysis in order to increase the specificity and sensitivity associated with the same risk, or for different groups of patients are scanned at the same time many loci. In contrast to predictive analysis, however, the diagnosis of a disease nor a direct presemptomatik genotiplemede purpose be a predisposing factor in the detection of the disease. The objective is to make the primary purpose and genetic structure of a pre-screening individuals by looking for convenient monitoring of environmental risk factors, modification, or low or high risk for certain diseases, is to appoint one of guruplarından.
Genotyping can be understood without a family history or genetic risk factors in terms of fully indicative of the data obtained in the absence of any other individual's genetic predisposition to the disease within the general desire for the purpose of the review and report on the most appropriate type of genetic analysis. However, genotyping can be performed on people who are still healthy, with a significant social or environmental factors that are at risk or already semptomat i k and watched, but atypical cases of the disease process or response to therapy as a first-line method of genetic analysis is extremely valuable.
Stem cell, and / or DNA banking, cell biology and molecular medicine, the rapid developments in order to be prepared for today is the most rational investment. After all, the thought into practice in recent years, different methods of treatment using stem cells, at least as fast and promising methods of gene therapy has shown an improvement. Moreover, advancing age and is known for a long time güçleşeceği supply of stem cell autograft. For such reasons, this subject is highly topical in our country started the first applications of cord blood banking style. However, genetic analysis should be noted that, without or without the DNA sample are analyzed the full content of the stem cells are stored frozen for the institution to which to store numbers that consist of only kartotekte. For this reason, here, with the DNA of stem cell banking as banking services, we'll discuss are inseparable.
DNA banking purposes disaggregated cells is stored in DNA molecules for use in advanced analysis to date. DNA in this manner can be stored for a long period of time known to a very low cost. What's more interesting clinical cases and experimental samples for DNA analysis have been supplying some of the fatal patients and their families bankalanması diagnostic or prognostic genetic tests to shed light on the future currency will gain a unique archive is also a fact that nature.
However, the scope of stem cell and DNA banking services, and service is of the essence in exchange for the mutual rights and demands a very clear written documentation must be completed. DNA banking, especially for some of the centers that offer this service for one-time charge in a single center, while most of the regular storage fees for an initial fee and subsequent attempt to actually remember.
