Genetic testing: no need for extremes!

A test or not a test?..

E. Sadykova, "Science in Siberia" No. 48-2012

Recently, a huge number of supposedly medical tests, including genetic ones, have appeared in the country and in the world. Moreover, in order to find the perfect couple, determine pregnancy or illness, it is not even necessary to contact any organizations, it is enough just to go online, the range of services is the widest.

We talked with Maxim Filipenko, Candidate of Biological Sciences, Head of the Pharmacogenomics Group at the Institute of Chemical Biology and Fundamental Medicine of the SB RAS, about how much we should trust testing.:

– Today, and not only in the scientific literature, there is a lot of talk about both the omnipotence of genetic testing and its complete uselessness, especially in the field of predicting the risk of complex diseases (based on both the influence of genes and many external factors, for example, lifestyle, diet, concomitant diseases, etc.). Despite the fact that for complex diseases this statement is really close to the truth, for a layman such statements may lead to underestimation of the role of genetic testing in modern medicine as a whole. This applies to monogenic diseases, for which genetic testing is useful not only from the point of view of predicting the risk of having sick children, but also from the point of view of disease management and treatment tactics.

Also today there are clinically useful tests that are not related to monogenic diseases. On the website of the FDA (the American agency that controls the appearance of new drugs, drugs, authoritative and for the whole world), among the list of recommended genetic tests, you can find many related to complex clinical signs. For example, hemostasis gene polymorphism tests for pregnant women and women using contraceptives, drug tolerance tests, etc.

When we started working in the field of genetic testing about seven years ago, we took two tests – the detection of the Leiden mutation and the mutation of the prothrombin gene. In fact, mutation is not a good word, these are some structural variants that can be neutral, bad or good, and sometimes their influence may depend on environmental conditions. It is believed that the Leiden mutation originated about 20-40 thousand years ago, it increases blood clotting. Modern people have a lot of food, obesity and physical inactivity, good sanitary conditions, high–quality medical care, so excessive blood clotting is not a good sign. It leads to the formation of blood clots, etc. But in those distant times, when it arose and spread, a woman gave birth literally under a bush, and her life and the life of her offspring depended on blood loss, this allelic structural variant gave good advantages. That is, different structural changes in different situations can have both a positive effect and a negative one. Moreover, if a mutation deprives a person of life (or makes him disabled) before he has offspring, it will begin to be progressively lost quickly. Although in this case there are mechanisms of its circulation in the population.

That is, there are quite "working" sets of certain structural variants of genes that we can determine, they are not related to monogenic diseases and are useful for predicting, for example, a person's response to medications, as well as helping to select the necessary dose.

Today, genetic studies of complex diseases are necessary primarily not to predict the risk of their occurrence, but in order to use them to understand which genes, which body systems are involved in the formation of these diseases.

Often genetic tests cannot accurately predict how high the risk of, for example, myocardial infarction is. The test may be incorrectly constructed from the point of view of informativeness, choosing it as a clinical diagnostic criterion. Nevertheless, there is a point of view that if, for example, a person got scared and stopped smoking after such genetic testing, then this test probably has the right to exist. And here we also immediately come across a lot of ethical aspects and problems.

Any new technology, any new knowledge (especially when it concerns our beloved health) entails a certain euphoria in its use. When polymerase chain reaction (PCR) appeared and it began to be used for testing infectious diseases, there was a period of this euphoria for some time, many said that it would displace other methods. But then it turned out that there are problems with its technical implementation, interpretation, and so on. Now PCR is a normal part of clinical diagnostics, without which there is nowhere. A period of euphoria, a period of disappointment passed, and after that we got down to business seriously, clearly, thoughtfully, having organized the process well. It seems to me that the same situation is with genetic testing. Of course, at some stage we will be able to select what is actually useful. Actually, we are still trying to do this.

But science is one thing, and the clinic is another. Doctors have their own ideas about treatment, schools. In fact, now there is a lot of information in the field of medicine, a lot of tests, drugs, and it is often difficult for a doctor to understand all this. But there is also the socio–economics of healthcare - you need to spend so much money on some tests and medicines that it is sometimes unprofitable for the state. All these aspects, hidden stones need to be taken into account.

But what our country currently has very serious problems with is that we have practically no promising programs that allow us to monitor large groups of people for a long time and check the informativeness of new tests (which now include genetic testing). And until the situation changes for the better, it is difficult to expect breakthroughs in domestic medical diagnostics.

Portal "Eternal youth" http://vechnayamolodost.ru10.12.2012