The genetic examination
What is a genetic test?
A genetic test describes an analysis of human DNA. The DNA is the carrier of the genetic material and is located in the cell nuclei, where it can be isolated using specific processes. The DNA can then be examined. The smallest mutations can influence gene expression and have health consequences. The diseases that arise here are quite different, as each gene has a different task.
Genetic tests allow the cause of certain diseases to be identified. In addition, the risk of suffering from a certain disease can be predicted.
The reasons for an investigation
The reasons for performing a genetic test can vary. If one suffers from an unclear illness or wants to confirm the suspicion of a mutation, the DNA can be analyzed. In addition, one can predict the risk of developing a certain disease. A classic example of this is the hereditary disease Huntington's disease.
In the case of familial breast cancer or colon cancer, it is advisable to carry out a genetic test. If there is a mutation that favors the development of cancer, preventive measures can be taken. In this case, preventive examinations are carried out at a younger age. In this way, tumorous changes can be discovered and treated at an early stage.
If you have several miscarriages and want to have children, a DNA test is a good idea. In addition, the DNA of the unborn child can be analyzed during pregnancy (so-called prenatal diagnosis). However, this is only allowed if there is a genetic defect that affects the child's health during or shortly after birth.
The breast cancer
Breast cancer is more common in some families because of a mutation in the BRCA-1 or BRCA-2 gene. These genes are known as tumor suppressor genes - that is, they regulate cell proliferation and prevent uncontrolled growth. But if these genes are mutated, they lose their function. As a result, the cells multiply in an uncontrolled manner and tumorous changes occur.
A BRCA mutation leads to a significant increase in the risk of developing breast cancer. In addition, the age is reduced - the cancer usually occurs before the age of 50. It also increases the risk of other forms of cancer. Ovarian cancer is particularly common.
An analysis of the BRCA gene is recommended if there is a noticeably large number in the family, if breast cancer occurs on both sides, or if men are affected.
These articles might also interest you:
- BRCA Mutation - Symptoms, Causes, Therapy
- The breast cancer gene
The desire to have children after miscarriages
Unfortunately, miscarriages are not as rare as one might think. Approximately 15% of all clinically confirmed pregnancies end prematurely. The causes are varied. Genetic, chromosomal defects, maternal diseases, placental disorders and other diseases are possible.
If 2 or more miscarriages have occurred and you still want to have children, clarification is required. The genetic test can identify the cause. In addition, the risk of repetition can be assessed and possibly also treated.
Find out all about the topic here: The miscarriage.
What genetic tests are there for hereditary diseases?
The principle of any genetic examination is DNA sequencing. The DNA is broken down into its building blocks, the gene segment to be examined is multiplied and then analyzed. Basically, a distinction can be made between genetic examinations that take place before birth (prenatal diagnosis) and examinations that take place during childhood and adulthood (postnatal diagnosis).
Various examinations are available prenatally, which are discussed in more detail in the next section. But there are also various methods of DNA analysis available postnatally. For example, a predictive test can be performed to see if there is a genetic change that could lead to the disease being examined. So the disease can be diagnosed before it breaks out. Accordingly, therapeutic measures can be carried out ahead of time.
The so-called heterozygous test describes a method where a healthy-looking person is examined. The aim here is to find out whether he / she is a carrier of a hereditary disease that could be passed on to the offspring.
What is a prenatal test?
A prenatal test is a genetic test of the unborn child. It may be necessary to do this if there are known genetic disorders in the family or if previous tests on the child suggest a genetic defect.
On the one hand, a chromosome examination can be carried out. Chromosomes are the carriers of the genetic make-up and can be incorrectly combined during fertilization, resulting in malformations or even miscarriages. Furthermore, tissue samples can be taken from the unborn child. For this, amniotic fluid is taken from which the child's cells can be isolated. This is followed by closer investigations.
The mother's blood can also be analyzed using molecular genetic methods. It can be checked whether a trisomy 21 is present. Another alternative in prenatal diagnosis is the triple test. Here, the mother's blood is tested for three specific hormones. Based on this, one tries to draw conclusions. However, this methodology is controversial.
Learn more about the topic: The prenatal diagnosis.
Preparing for the examination
The preparation for the examination includes an indication - it must be clear why one would like to carry out a genetic examination. In addition, the patient should be informed about possible effects and changes in his life if the test result should be positive.
After a certain period of reflection, the examination can be carried out, but the patient must agree in writing, as there is a genetic diagnosis law in Germany that strictly regulates DNA analyzes
The sequence
Depending on which test is carried out, either blood must be drawn from the patient or saliva can be removed from the oral mucosa with a cotton swab. In some tests you can also shed hair.
The material obtained is then sent to a laboratory. There the DNA is extracted from the cell nucleus. The gene segment to be examined is multiplied (so-called polymerase chain reaction) and examined in terms of molecular genetics. After the necessary analyzes, the results are communicated to the attending physician, who should discuss them with you in detail.
The evaluation
After the molecular genetic studies, the results are compiled. The guidelines are databases that were previously created in large studies. The result with is compared with this database and is usually very reliable. However, a positive result does not 100% mean that you are ill. Many mutations have no effect because they are neutral mutations. In addition, the genes have different penetrances. Put simply, it means that the expression of genes varies from person to person.
The doctor treating you should definitely explain the result to you again, as this is a more complex topic.
The risks
Postnatal diagnosis is actually hardly risky. Usually, a simple blood sample or saliva is sufficient for the analysis. However, life may change completely after a positive test result. Unfortunately, some hereditary diseases are incurable and can cause psychological stress. Social isolation is also conceivable. For this reason, the patient should be informed before the implementation so that he is aware of any consequences.
The risk of prenatal diagnosis varies and has more risks depending on the test method. An amniotic fluid test or biopsy of the placenta may result in bleeding or loss of amniotic fluid. The most feared complication is miscarriage, which only occurs in 0.5% of cases.
This article might also interest you: The amniotic fluid deficiency.
The duration of the results
The duration of the results can vary widely. It depends on which test is done.
Blood examinations usually take a shorter time than molecular genetic methods, as the procedure is more complex. If you want an exact time, you should discuss this with your doctor or laboratory.
How reliable are the results?
The reliability of the result can vary depending on where you have it performed. As a rule, tests that are supervised by a human geneticist are very reliable. Human geneticists are doctors who have completed their specialist training in genetics. If you want a genetic clarification, it is advisable to visit a human geneticist and get advice. You decide which tests should be carried out and work with reputable laboratories.
Nowadays, genetic tests can also be bought on the Internet. In this case, however, one does not know which laboratory is carrying out the tests and how reliable they are. For this reason, this alternative is not particularly recommended.
The costs
A general statement about the costs cannot be made. Different test procedures are necessary depending on the medical indication. For example, a blood test of the mother in prenatal diagnosis is cheaper than an amniotic fluid test.
In some cases, the costs can also vary depending on the laboratory. However, in rare cases the costs have to be borne by the patient - these are usually covered by the health insurance company.
Does the health insurance pay for that?
In many cases, the statutory health insurance pays the costs of genetic counseling. There are two regulations where it does not. On the one hand, if there is no medical indication, for example in a DNA family tree test. Here the patient would like to have his DNA analyzed out of self-interest.
On the other hand, special regulations apply if the DNA analysis is to be carried out in connection with fertility treatment. In this case there is an additional payment obligation. If this special regulation applies to you, you should find out more from your health insurance company before the examinations.
Privately insured patients may have to cover part of the costs themselves. However, this depends on the health insurance company. For this reason, you should check with your health insurance company in advance.
What are the alternatives?
There is no real alternative to genetic testing. If a genetic disease is suspected, only a DNA analysis can provide the necessary information. It can be used to confirm or exclude the disease. Blood tests or imaging tests are out of the question as alternatives. They can only point the way.
If genetic diseases are known in relatives and you want to assess the risk of passing the disease on to your descendants, a DNA analysis is recommended. Unfortunately, there are no alternative procedures for this risk assessment.
Find out more about the here Structure of DNA.
