Implementation

Anyone who wants to have a genetic test performed must first attend a genetic consultation in Germany. Here a consultation is carried out with a doctor who has been trained in human genetics or has an additional qualification. It makes sense to think about the family tree at home before the consultation.

Questions about illnesses of other blood-related family members are usually asked, so it is wise to get some detailed information from the family beforehand. As a rule, the genetic test is preceded by other diagnostic procedures to determine a suspected diagnosis. Before genetic testing is carried out, extensive information must be provided about the risks and consequences of genetic testing.

In addition to medical risks, the possible results and the resulting medical or psychological consequences must be discussed. No genetic test can be performed without the consent of the person concerned. Subsequently, genetic testing can confirm the diagnosis.

For this purpose, materials containing the genetic material must be obtained. In most cases, a simple blood sample is sufficient to examine the cells it contains. For molecular genetic testing, however, nucleated cells are needed, which can be obtained, for example, by taking smears of cells from the oral mucosa or bone marrow.

After the mandatory genetic counselling as stipulated in the Genetic Diagnostics Act, in which a complete explanation of the procedure is given, a declaration of consent is signed. Afterwards the sample is collected in the form of saliva with a cotton swab in the mouth.Alternatively, you can use blood or other materials such as hair. However, only saliva and blood/cord blood are common.

The samples are prepared and examined in a laboratory. In the laboratory, various tests can be carried out using a number of biochemical processes in order to identify certain gene errors or gene sequences. The best known test is the so-called “PCR”, short for “polymerase chain reaction”.

In order to carry out the test, it is necessary to know in advance which gene sequence is being searched for in order to detect whether this gene segment is present or not. This gene sequence is then reproduced many times and thus made visible. The result of the analysis may only be opened by the treating physician and nobody else.

At a further appointment, the doctor will explain the result of the analysis and a decision can be made whether further procedures are necessary. The duration of the genetic test depends on the genetic material to be examined and the suspected disease. Chromosome analyses require less time than complex molecular genetic analyses.

For an average chromosome analysis, the working time is about 10-20 working days. Prenatal diagnostic examinations are usually performed more quickly. A chromosome analysis based on sample tissue from the placenta can be performed within a few days.

Cells from the amniotic cavity, however, must first grow and mature artificially, which can take between 2 and 3 weeks. Molecular genetic analyses take different lengths of time, depending on the number of genes to be examined and the size of the gene sequences. These analyses can take weeks to months.

Medically, the risks of a genetic test are very low. In most cases, saliva or blood samples are sufficient for gene analysis. A genetic test of the bone marrow cells is usually only performed if the bone marrow puncture would have been indicated anyway.

This leaves medically the very rare risks of injury or infection from the puncture. However, the evaluation of the genetic test results can be risky. Before the test is performed, an informative conversation should be held with the physician to explain the consequences and the significance of the genetic test.

The risk is that possible illnesses are not recognized and that those affected are lulled into a false sense of security. A negative result for an illness is in fact no guarantee not to fall ill. It can either be a false negative result or a spontaneous mutation that causes the disease.

On the other hand, it is possible that false results lead to emotional stress and intensive therapies, although there is no danger at all. The risk of these erroneous evaluations and misinterpretations of the test results increases with commercial genetic tests that are performed without the involvement of a physician. In a laboratory, the sample is examined using a procedure appropriate to the sample.

In principle, only what is requested by the physician is examined. One only receives an answer to a specific question. The laboratory thus only determines whether the gene sequences sought are present in the cells of the person examined.

A doctor must then evaluate what this means for the diagnosis, the disease and the subsequent therapy. The genome is not analyzed completely. This is because human genetics is still greatly overestimated in its capabilities and experience is not yet sufficient to reliably analyze such large quantities.

Thus it can happen that incorrect assignments are made due to the numerous small gene segments. The risk of errors therefore decreases with the specific question being asked. However, this does not have to be the case forever.

The genome analysis is constantly becoming more precise and more and more segments are being decoded. If a certain faulty gene could be detected, which occurs for example in cystic fibrosis, the diagnosis is thus clearly confirmed. Thus, appropriate therapies may have to be initiated immediately.

Predictive tests, such as the genetic modification of the “BRCA” genes before the onset of cancer, can have different consequences. In addition to more stringent diagnostic procedures, preventive breast removal and radical therapy options are offered for prevention. The decision is ultimately made by the patient.