27 prevention, diagnosis and treatment of hereditary diseases. Hereditary diseases. Referral to medical genetic consultation is subject to

The environment has never been constant. Even in the past she was not completely healthy. However, there is a fundamental difference between the modern period in human history and all previous ones. IN Lately The pace of environmental change has become so accelerated, and the range of change has expanded so much, that the problem of studying the consequences has become urgent.

The negative influence of the environment on human heredity can be expressed in two forms:

environmental factors can “wake up” a silent gene or silence a working gene,

environmental factors can cause mutations, i.e. change a person's genotype.

To date, the burden of mutations in human populations has amounted to 5%, and the list of hereditary diseases includes about 2000 diseases. Neoplasms caused by mutations in somatic cells cause significant harm to humanity. An increase in the number of mutations entails an increase in natural miscarriages. Today, up to 15% of fetuses die during pregnancy.

One of the most important tasks of today is the creation of a monitoring service for the human gene pool, which would record the number of mutations and the rate of mutation. Despite the apparent simplicity of this problem, its real solution faces a number of difficulties. The main difficulty is the enormous genetic diversity of people. The number of genetic deviations from the norm is also huge.

Currently, deviations from the norm in the human genotype and their phenotypic manifestation are dealt with by medical genetics, within the framework of which methods for the prevention, diagnosis and treatment of hereditary diseases are being developed.

Methods for the prevention of hereditary diseases.

Prevention of hereditary diseases can be carried out in several ways.

A) Activities may be carried out aimed at weakening the effect of mutagenic factors: reducing the radiation dose, reducing the amount of mutagens in the environment, preventing the mutagenic properties of serums and vaccines.

B) A promising direction is search for antimutagenic protective substances . Antimutagens are compounds that neutralize the mutagen itself before it reacts with the DNA molecule or remove damage from the DNA molecule caused by mutagens. For this purpose, cysteine is used, after the introduction of which the mouse’s body is able to tolerate a lethal dose of radiation. A number of vitamins have antimutagenic properties.

C) Serves for the purpose of preventing hereditary diseases genetic counseling. At the same time, closely related marriages (inbreeding) are prevented, since this sharply increases the likelihood of having children homozygous for an abnormal recessive gene. Heterozygous carriers of hereditary diseases are identified. A geneticist is not a legal entity; he cannot prohibit or allow those being consulted to have children. Its goal is to help the family realistically assess the degree of danger.

Methods for diagnosing hereditary diseases.

A) Method of mass (sifting) diagnostics .

This method is used in newborns to identify galactosemia, sickle cell anemia, and phenylketonuria.

B) Ultrasound examination.

In the 70s, at the 1st International Genetic Congress, the idea was voiced of introducing medical practice prenatal diagnosis of hereditary diseases. Today, the most widely used method is ultrasound examination. Its main advantage is the widespread nature of the examination and the ability to identify abnormalities at 18–23 weeks of pregnancy, when the fetus is not yet viable on its own.

IN) Amniocentesis.

At 15-17 weeks of pregnancy, the amniotic sac is pierced with a syringe and sucked out a small amount of fetal fluid, which contains desquamated cells of the fetal epidermis. These cells are grown in culture for 2–4 weeks on special nutrient media. Then using biochemical analysis and studying the chromosome set, it is possible to identify about 100 gene and almost all chromosomal and genomic anomalies. The amniocentesis method has been successfully used in Japan. Here, all women over 35 years of age, as well as women who already have children with abnormalities, are examined free of charge. Amniocentesis is a relatively time-consuming and expensive procedure, but economists have calculated that the cost of the test for 900 women is much cheaper than the cost of lifetime hospitalization for one patient with hereditary anomalies.

G) Cytogenetic method.

Human blood samples are studied to determine chromosomal abnormalities. This is especially important when determining the carriage of diseases in heterozygotes.

D) Biochemical method.

Based on genetic control of protein synthesis. Registration of different types of proteins allows us to estimate the frequency of mutations.

Methods of treating hereditary diseases.

A) Diet therapy.

It consists of establishing a properly selected diet that will reduce the severity of the disease. For example, with galactosemia, a pathological change occurs due to the fact that there is no enzyme that breaks down galactose. Galactose accumulates in cells, causing changes in the liver and brain. Treatment of the disease is carried out by prescribing a diet that excludes galactose in foods. The genetic defect is preserved and passed on to offspring, but the usual manifestations of the disease in a person using this diet are absent.

B ) Introduction of the missing factor into the body.

For hemophilia, injections of a protein are performed, which temporarily improves the patient's condition. In the case of hereditary forms of diabetes, the body does not produce insulin, which regulates carbohydrate metabolism. In this case, insulin is injected into the body.

IN) Surgical methods.

Some hereditary diseases are accompanied by anatomical deviations from the norm. In this case, surgical removal of organs or their parts, correction, and transplantation are used. For example, in case of polyposis, the rectum is removed and congenital heart defects are operated on.

G) Gene therapy– elimination of genetic errors. To do this, a single normal gene is included in the somatic cells of the body. This gene will replace the pathological gene as a result of cell proliferation. Gene therapy through germ cells is currently carried out in animals. A normal gene is inserted into an egg with an abnormal gene. The egg is implanted into the female's body. From this egg, an organism with a normal genotype develops. Gene therapy is planned to be used only in cases where the disease is life-threatening and cannot be treated by other means.

Behind the pages of a school textbook.

Some questions of eugenics.

The idea of artificial human enhancement is not new. But only in 1880. The concept of “eugenics” appeared. This word was introduced by Charles Darwin’s cousin, F. Galton. He defined eugenics as the science of the improvement of offspring, which is by no means limited to questions of intelligent crossbreeding, but, especially in the case of man, deals with all influences that are capable of giving the most gifted races the maximum chance of prevailing over the less gifted races.

The term "eugenics" comes from the Greek word for human good kind, noble birth, good race.

Galton certainly recognized a certain role of environment in the development of the individual, but ultimately he believed that “race” was more important than environment, i.e. he emphasized what we today call the genetic factor.

The idea of improving human populations using biological methods has a long history. Historians have found arguments of this type even in Plato. Nevertheless, Galton was original in developing a complete theory. His works represent the main source to which one should turn when analyzing what is happening today. According to Galton, eugenics, which he founded, deserved the status of a science. From a certain angle, eugenics does contain something scientific; it uses some theories and results from the fields of biology, anthropology, demography, psychology, etc. It is obvious, however, that the basis of eugenics is social and political. The theory had a practical ultimate goal - to preserve the most “gifted races” and increase the number of the nation’s elite.

Influenced by his own failures that befell him at Cambridge, Galton became closely interested in the following problem: what is the origin of the most gifted people. He wrote works in which, with the help of statistics, he tried to confirm the hypothesis, prompted by his personal beliefs, that the most gifted individuals are often close relatives of people who are also gifted. Galton's principle of research was simple: he studied populations of people belonging to the social elite (judges, statesmen, scientists). He identified a fairly significant number of their close relatives, who were themselves prominent figures. Comparisons were made methodically, taking into account varying degrees kinship. The correlations thus established were clearly unstable and limited. In reality, the interpretation of these statistics in favor of the biological inheritance thesis was by no means obvious. But Galton himself belonged to the English elite, so psychologically it was quite easy for him to allow the inheritance of genius.

In the history of biology, Galton's role is usually underestimated. Biologists did not perceive Galton as a specialist: his biological interests were subordinated more common interests. And yet, it was he who, 10 years before Weissman, formulated the two main provisions of his theory. Galton took an interest in genetics and due to what he attributed to heredity important role in social phenomena.

The application of eugenics in the field of science in some cases proves fruitful, but in general eugenics lacks a scientific basis. The project of improving individual races, the most gifted, is based primarily on ideological and political motives. The fact that genetics can provide eugenicists with some arguments does not at all prove either the truth or the ethical legitimacy of this project. The concept of “race” in Galton’s interpretation is very flexible. First of all, it may correspond to the common idea of race: yellow, white, black. He uses the concept of “race” more flexibly: a race is formed by any homogeneous population in which certain characteristics are consistently inherited. This idea is highly controversial. The criteria for a “good race” are themselves rather vague, but the main ones are such qualities as intelligence, energy, physical strength and health.

In 1873 Galton published an article “On the Improvement of Heredity.” In it, he explains that the first duty of humanity is to voluntarily participate in general process natural selection. According to Dalton, people must do methodically and quickly what nature does blindly and slowly, namely, favor the survival of the most worthy and slow down or interrupt the reproduction of the unworthy. Many politicians listened favorably to such statements. Impressive figures were given: between 1899 and 1912. In the US, 236 vasectomies were performed on mentally retarded men in the state of Indiana. The same state in 1907 voted for a law providing for the sterilization of hereditary degenerates, then California and 28 other states did the same. In 1935 total number sterilization operations reached 21,539. Not all eugenic measures were so crude, although they were based on the same philosophy of selecting the most gifted people. It is noteworthy that men of science, of great repute, did not hesitate to propose very severe measures. Nobel Prize winner Frenchman Karel in 1935. published his work “This Unknown Creature is a Man,” which was an extraordinary success. In this book, the author explained that given the weakening of natural selection, it was necessary to restore the “biological hereditary aristocracy.” Regretting the naivety of civilized nations, which manifests itself in the preservation of useless and harmful creatures, he advised the creation of special institutions for the euthanasia of criminals.

Thus, the concept of “eugenicism” covers diverse manifestations of reality, but all diversity can be reduced to two forms: militant (conscious) eugenicism and “soft” (unconscious) eugenicism. The first one is the most dangerous. It was he who gave birth to the Nazi gas chambers. But it would be a mistake to consider the second harmless. It is also characterized by ambiguity: some activities related to the identification and prevention of hereditary diseases represent a rudimentary form of eugenics.

The difference between eugenicism and social Darwinism.

Proponents of Social Darwinism preach laissez-faire. They believe that competition between people is beneficial and that the struggle for existence will ensure the survival of the best individuals, so it is enough not to interfere with the spontaneous selection process.

As for eugenics, there is something of a policeman inherent in it: its goal is to establish an authoritarian system capable of producing “scientifically” the good individuals and good genes that the nation needs. It’s easy to go downhill here: they start with establishing genetic identity maps, increase the number of tests to determine suitability for marriage, close the channels leading to vicious elements, and then comes the turn of the final act, for example, euthanasia - humane and economical. Nazi eugenics had a super-scientific basis. Hitler, in order to justify the cult of the “pure race,” explicitly refers to the biology of reproduction and the theory of evolution.

What does it mean to be a eugenicist today?

The situation has changed greatly since Galton's time. The years of Nazism led to the fact that eugenics had to retreat in ideological and social terms. But enormous advances in biology and genetic engineering made the emergence of neo-eugenics possible. The big innovation was the development of methods to identify “bad” genes, i.e. genes responsible for diseases. Genetic defects can be detected using different stages. In some cases, people who want to have children are examined, in others, pregnant women are examined. If a serious anomaly is detected in the fetus, the question of abortion may be raised. By identifying serious genetic errors in newborns, early treatment can restore lost function. Thus, a new situation has arisen: from now on it is possible to plan a grandiose long-term surgery for a major cleansing of the human gene pool. This raises numerous questions, both technical and ethical. First of all, where to stop when culling genes? The ideal of merciless genetic selection seems controversial in biological terms;6 could such selection lead to the impoverishment of the gene pool of humanity? The dream of eugenicists is to use gene selection akin to selection in animal husbandry. But it was the livestock breeders who had the opportunity to be convinced that systematic selection can only be used to a certain limit: if a variety is improved too much, its viability is sometimes excessively reduced. There are currently two main trends opposing each other. One camp consists of supporters of tough measures. They believe that Genetic Engineering gave into the hands of man a weapon that should be used for the benefit of humanity. For example, Nobel Prize winner in Physiology or Medicine Lederberg is a proponent of cloning human genes as an effective means of creating extraordinary people. In the other camp are those who demand that the field of human genetics be declared inviolable. In the USA, thanks to a private initiative, the collection and preservation of sperm from Nobel Prize winners has already been organized. Thus, if we believe those in charge, it will be possible to easily produce children with outstanding talents through artificial insemination. In reality, there is nothing to suggest that such a project is scientifically justified.

A number of facts indicate that today there are simultaneously various reasons contributing to the resurrection of eugenics.

Thuillet P. “The temptations of eugenicism.”

In the book. "Genetics and heredity." M.: Mir, 1987.

Interest in the problem of hereditary diseases is growing as the number of hereditary pathologies among the population increases. Moreover, this growth is due not so much to the absolute increase in the number of hereditary diseases, but to the improvement in the diagnosis of previously unknown forms. It is becoming increasingly clear that knowledge of the causes and mechanisms of development of hereditary human diseases is the key to their prevention.
One of the ways to prevent hereditary diseases is to prevent the action of factors external environment, contributing to the manifestation of a pathological gene

Prevention:(Slide 26)

Medical genetic counseling during pregnancy at the age of 35 years and older in the presence of hereditary diseases in the pedigree
Exclusion of consanguineous marriages. However, some Indian tribes were described in which no hereditary diseases occurred in consanguineous marriages for 14 generations. It is known, for example, that Charles Darwin and Abraham Lincoln were born from consanguineous marriages. Darwin himself was married to his cousin, and the three sons born in this marriage were absolutely healthy and later became famous scientists. A.S. Pushkin was born from the marriage of S.L. Pushkin with his second cousin Nadezhda Hannibal.

Genetic consultation. The reasons for seeking genetic counseling can be very different. For example, parents can contact it if they are afraid of having a child with a genetically determined disease. Genetic studies can predict the likelihood of such diseases if, for example:

Parents have genetic disease in the family;
A married couple already has a sick child;
IN married couple the wife had multiple miscarriages;
Elderly couple;
I have relatives with genetic diseases.

A prerequisite for effective consultation is, if possible, a detailed analysis of family pedigrees regarding hereditary diseases.

Heterozygosity test allows us to draw conclusions regarding genetically determined metabolic defects that appear in parents in an erased form, since heterozygous carriers of the trait synthesize regulatory substances in small quantities.

Prenatal (prenatal) diagnosis. In this diagnosis, several milliliters of amniotic fluid are taken from the amniotic sac. The fetal cells contained in the amniotic fluid allow us to draw conclusions about both metabolic disorders and chromosomal and gene mutations.

Treatment:(Slide 27)

Diet therapy
Replacement therapy
Removal of toxic metabolic products
Mediometori effect (on enzyme synthesis)
Exclusion of certain medications (barbiturates, sulfonamides, etc.)
Surgery

Today it is actively developing new method – gene therapy. It can be used to heal a person with a genetically determined disease, or at least reduce the severity of the disease. With this method, defective genes can be replaced by “healthy” ones and the disease can be stopped by eliminating the cause (defective gene). However, targeted interference with human genetic information carries the risk of abuse through manipulation of germ cells, and is therefore actively disputed by many. Although most genetic engineering research is at the laboratory testing stage, further development This direction allows us to hope for the practical use of the method for treating patients in the future.

Eugenics(from the Greek ευγενες - “good kind”, “thoroughbred”) - a form of social philosophy, the doctrine of a person’s hereditary health, as well as ways to improve his hereditary properties. Eugenics is also the name given to the social practice associated with this philosophy. In modern science, many problems of eugenics, especially the fight against hereditary diseases, are solved within the framework of human genetics. The ideas of eugenics were discredited because they were used to justify anti-humanistic theories (for example, fascist racial theory). Researchers use population genetics methods and study the frequency and dynamics of genetically determined defects and the genes responsible for these defects in human populations. The goals of eugenics are:

research and consultations on issues of inheritance, that is, the transmission to descendants of genes that cause diseases, and, accordingly, their prevention;
study of changes in human hereditary information under the influence of factors environment, manifested in genetic characteristics;
preservation of the human gene pool.

3.4. Treatment and prevention of some hereditary human diseases

The increased interest of medical genetics in hereditary diseases is explained by the fact that in many cases, knowledge of the biochemical mechanisms of development makes it possible to alleviate the suffering of the patient. The patient is injected with enzymes that are not synthesized in the body. For example, diabetes mellitus is characterized by an increase in the concentration of sugar in the blood due to insufficient (or complete absence) the production of the hormone insulin by the pancreas in the body. This disease is caused by a recessive gene. Back in the 19th century, this disease almost inevitably led to the death of the patient. Extracting insulin from the pancreas of some pets has saved the lives of many people. Modern methods of genetic engineering have made it possible to obtain insulin at a much higher High Quality, absolutely identical to human insulin on a scale sufficient to provide every patient with insulin and at much lower cost.

Nowadays, hundreds of diseases are known in which the mechanisms of biochemical disorders have been studied in sufficient detail. In some cases modern methods microanalyses make it possible to detect such biochemical disorders even in individual cells, and this, in turn, makes it possible to diagnose the presence similar diseases in an unborn child by individual cells in the amniotic fluid.

3.5. Medical genetic counseling

Knowledge of human genetics allows us to predict the likelihood of having children suffering from hereditary diseases, when one or both spouses are sick or both parents are healthy, but the hereditary disease occurred in the ancestors of the spouses. In some cases, it is possible to predict the probability of having a second child. healthy child, if the first one was affected by a hereditary disease.

As the biological and especially genetic education of the general population increases, married couples who do not yet have children are increasingly turning to geneticists with the question of the risk of having a child affected by a hereditary anomaly.

Medical genetic consultations are now open in many regions and regional centers of our country. The widespread use of medical and genetic consultations will play an important role in reducing the incidence of hereditary diseases and will save many families from the misfortune of having unhealthy children.

Currently, the amniocentesis method is widely used in many countries, allowing the analysis of embryonic cells from amniotic fluid. Thanks to this method, a woman can get important information about possible chromosomal or gene mutations of the fetus and avoid the birth of a sick child.

Conclusion

So, the work outlined key concepts genetics, its methods and achievements recent years. Genetics is a very young science, but the pace of its development is so high that currently it occupies the most important place in the system modern sciences, and, perhaps, the most important achievements of the last decade of the past century are associated precisely with genetics. Now, at the beginning of the 21st century, prospects are opening up before humanity that captivate the imagination. Will scientists be able to realize the gigantic potential inherent in genetics in the near future? Will humanity receive the long-awaited deliverance from hereditary diseases, will man be able to prolong his life too long? short life, gain immortality? At present we have every reason to hope for this.

According to geneticists, by the end of the first decade of the 21st century, genetic vaccines will replace conventional vaccinations, and doctors will have the opportunity to forever put an end to such incurable diseases as cancer, Alzheimer's disease, diabetes, and asthma. This direction already has its own name - gene therapy. She was born just five years ago. But it may soon lose its relevance thanks to gene diagnostics. According to some forecasts, around 2020, only healthy children: already at the embryonic stage of fetal development, geneticists will be able to correct hereditary problems. Scientists predict that in 2050 there will be attempts to improve the human species. By this time, they will learn to design people of a certain specialization: mathematicians, physicists, artists, poets, and perhaps geniuses.

And closer to the end of the century, man’s dream will finally come true: the aging process, undoubtedly, can be controlled, and then immortality will not be far away.

Literature.

N. Grinn, Biology, Moscow, MIR, 1993.

F. Kibernstern, Genes and genetics. Moscow, “Paragraph”, 1995.

R.G. Hare et al., Biology for university applicants. MN: Higher School, 1999

M.M.Tikhomirova, Genetic analysis: tutorial. – L.: Leningrad University Publishing House, 1990.

General biology. A textbook for grades 10-11 in schools with in-depth study of biology. Edited by Professor A.O. Ruchinsky. Moscow, “Enlightenment” 1993.

Nature. 1999. pp. 309-312 (Great Britain).

Heredity and genes, Science and Life, March 1999

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1. Treatment of hereditary diseases:

1. Symptomatic and pathogenetic - impact on the symptoms of the disease (the genetic defect is preserved and passed on to offspring):

1) diet therapy, which ensures the entry of optimal quantities of substances into the body, which relieves the manifestation of the most severe manifestations of the disease - for example, dementia, phenylketonuria.

2) pharmacotherapy (introduction of the missing factor into the body) - periodic injections of missing proteins, enzymes, Rh factor globulins, blood transfusions, which temporarily improves the condition of patients (anemia, hemophilia)

3) surgical methods- organ removal, damage correction or transplantation (cleft lip, birth defects hearts)

2. Eugenic measures - compensation for natural human shortcomings in the phenotype (including hereditary ones), i.e. improving human health through phenotype. They consist of treatment with an adaptive environment: prenatal and postnatal care for offspring, immunization, blood transfusions, organ transplantation, plastic surgery, diet, drug therapy etc. It includes symptomatic and pathogenetic treatment, but does not completely eliminate hereditary defects and does not reduce the number of mutant DNA in the human population.

3. Etiological treatment - impact on the cause of the disease (should lead to a radical correction of anomalies). Not currently developed. All programs in the desired direction of fragments of genetic material that determine hereditary anomalies are based on the ideas of genetic engineering (directed, reverse induced mutations through the discovery of complex mutagens or the replacement of a “sick” chromosome fragment in a cell with a “healthy” one of natural or artificial origin)

2. Prevention of hereditary diseases:

Preventive measures include medical genetic consultations, prenatal diagnosis and medical examination. In many cases, specialists can indicate to parents the likelihood of having a child with certain defects, chromosomal disease or metabolic disorders caused by gene mutations.

Medical genetic counseling. The tendency towards weight gain due to hereditary and genetically determined pathologies is quite clearly expressed. The results of population studies in recent years have shown that on average 7-8% of newborns are diagnosed with some kind of hereditary pathology or developmental defects. The most the best method The cure for a hereditary disease would be to correct the pathological mutation by normalizing the chromosomal or gene structure. “Reverse mutation” experiments are carried out only in microorganisms. However, it is possible that in the future genetic engineering will correct the mistakes of nature in humans. So far, the main way to combat hereditary diseases is to change environmental conditions, as a result of which the development of pathological heredity becomes less likely, and prevention through medical genetic counseling of the population.

The main goal of medical genetic counseling is to reduce the incidence of diseases by limiting the appearance of offspring with hereditary pathology. And for this it is necessary not only to establish the degree of risk of having a sick child in families with a family history, but also to help future parents correctly assess the degree of real danger.

The following are subject to referral to medical genetic consultation:

1) patients with hereditary diseases and members of their families;

2) members of families in which there are repeated cases of illness of unknown cause;

3) children with developmental defects with suspected chromosomal disorders;

4) parents of children with established chromosomal disorders;

5) spouses with repeated spontaneous abortions and infertile marriages;

6) patients with disorders of sexual development

7) persons wishing to marry if one of them or one of their relatives suffers from hereditary diseases.

In a medical genetic consultation, the patient is examined and a family pedigree is compiled. Based on the data obtained, the type of inheritance is assumed of this disease. In the future, the diagnosis is clarified either by studying the chromosome set (in a cytogenetic laboratory), or with the help of special biochemical studies (in a biochemical laboratory).

For diseases with a hereditary predisposition, the task of medical genetic counseling is not to predict the disease in the offspring, but to determine the possibility of developing this disease in the patient’s relatives and develop recommendations if treatment or appropriate preventive measures are necessary. Early prevention aimed at eliminating harmful factors, provoking the development of the disease, has great value, especially when high degree predisposition. To diseases in which such preventive actions turn out to be effective, primarily hypertonic disease with its complications ischemic disease hearts and strokes, peptic ulcer, diabetes.

27 prevention, diagnosis and treatment of hereditary diseases. Hereditary diseases. Referral to medical genetic consultation is subject to

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