What diseases are called hereditary? Abstract on biology on the topic: Hereditary human diseases read. Biology of hereditary diseases

Scientists say that a person’s appearance, health status and other individual characteristics depend on two main factors: genetics and environmental influences. Moreover, genetics accounts for 70%.

Most diseases are, to one degree or another, related to heredity: sometimes genetics increases the risk of developing a certain disease, but there are also a number of ailments directly related to a breakdown in the genetic apparatus.

However, not all is lost: each of us has a chance to influence our destiny, because 30% of health depends on lifestyle, nutrition, physical activity and the efforts of doctors.

Features of diseases transmitted by inheritance

Congenital and hereditary diseases are not the same thing, although both begin from the moment the baby is born.

Congenital diseases are formed as a result of disruption of pregnancy, the influence of alcohol, nicotine, certain medications and diseases (viral hepatitis,). However, the fetus was initially healthy.

Diseases with a hereditary predisposition do not leave the child even a ghostly chance. In this case, the breakdown occurs much earlier - at the stage of transfer of genetic material from parents to children.

The second feature of hereditary diseases is the impossibility of a complete cure. Pneumonia and sore throat can be cured by taking antibiotics; an inflamed appendix or gallbladder can be removed. But it is not yet possible to correct the genetic material. Scientists are trying to correct the genetic material, but they are still far from introducing their findings into widespread practice.

The only possible way to treat hereditary diseases is therapy aimed at eliminating symptoms and improving the quality of life. In some cases, drug prevention of exacerbations is effective, but the prognosis still remains disappointing. Hereditary diseases, unfortunately, are still incurable.

Myopia is the most common hereditary disease.

5 most popular hereditary diseases

Myopia

This is perhaps one of the most common diseases that is directly inherited. Of course, poor reading posture, frequent television watching, sitting in front of a laptop screen for many hours every day and lack of sufficient vitamin A in the diet also play a role in vision deterioration.

However, in the same school class there will be children who behave the same way - while one is already wearing glasses, and the other can see clearly. The main cause of myopia is family history.
The cause of the disease is a feature of the muscles that help stretch the eyeball. As a result, the image is focused not on the retina, but closer, and the person sees blurred.

If the mother or father suffered from myopia, then the probability of transmission to the child is 30-40%, and if both - then 70%. The disease most often manifests itself during a period of active growth - in adolescence, but even a junior schoolchild can get sick.

This is a classic hereditary disease. There are several subtypes of hemophilia, in which the breakdown leads to disruption of the production of individual clotting factors. The severity also varies. There are three types of the disease: hemophilia A, B and C.

The mutation that causes hemophilia is linked to the X chromosome. Women have two X chromosomes, so if one of them has this anomaly, then the lady is not sick, but simply becomes a carrier. History contains only 60 cases when the pathology affected two chromosomes at once, and the woman fell ill.

Almost all patients with hemophilia are boys, because they have one X chromosome. One of the most famous hemophiliacs was the young Tsarevich Alexei Nikolaevich. By the day of his execution at the age of 14, the boy was in extremely serious condition.

Thrombophilia

Thrombophilia is a pathological condition in which blood clotting increases. There are many types of thrombophilia in which mutations occur in individual parts of the coagulation system (for example, deficiency of antithrombin, protein C and S, and antiphospholipid syndrome).

Many people think that this condition is rare and it will not affect them. And yet, it is thrombophilia that often leads to ischemic heart attacks, strokes, pulmonary embolism, and vascular thrombosis in people under 40 years of age.

Thrombophilia is often detected during examination for recurrent miscarriages and failure to carry a pregnancy to term in women. Unfortunately, there is a high probability that the children of patients will inherit this condition.

This disease occurs in one in 2,500 newborns, which is not that rare. Cystic fibrosis is inherited in an autosomal recessive manner. That is, in order for a sick child to be born, the baby must receive the wrong gene from the mother and father at the same time.

Between 2 and 5% of people worldwide are carriers of cystic fibrosis and have no idea about it. If they meet someone like him, they can give birth to a sick child with a 25% chance.
Cystic fibrosis is associated with a decrease in secretion production by all glands of the body. As a result, the functioning of the respiratory and digestive systems is disrupted. In particular, secretions are not released from the lumen of the bronchi during respiratory diseases, and there is no production of enzymes for digesting food by the pancreas.

Treatment consists only of replacement therapy, and the prognosis remains unfavorable. In Europe, such people live up to 40 years, in Russia - up to a maximum of 28.

Muscular dystrophy

This terrible disease includes several subspecies (Erba-Rota, Landouzi, Duchenne). The essence of the disease is progressive muscle weakness, gradually leading to complete immobility of a person.

However, given the fact that the disease is transmitted with a recessive gene, a child with muscular dystrophy can be born to apparently healthy parents. It is enough that the probability of carrier status in the parents is 25%.

As a rule, doctors detect the first signs of Duchenne myopathy at the age of 6 months. Sometimes they are even “written off” as a complication of DTP vaccination, which is fundamentally incorrect, because the disease is hereditary. Erb-Roth's youth form debuts at 14-16 years of age.

Treatment of muscular dystrophy is symptomatic and is aimed only at improving the quality and maximizing prolongation of life.

Scientists do not yet know how to cure genetic diseases, but such attempts are being made all over the world.

Can genetic diseases be prevented?

It is currently impossible to prevent the occurrence of hereditary diseases. However, you can be tested for the most common types of mutations and identify the likelihood of having a child with pathology in a particular couple.

Then a lot depends on the behavior of the parents. Lifestyle changes, of course, will not affect the genetic material, but in some cases it reduces the risk of severe manifestations of the disease.
Therefore, you should not be afraid of genetic tests: the earlier the diagnosis is made, the easier it will be to help the child.

If you don't know which laboratory to contact, Medical Note's medical concierge will select a free laboratory that can perform a genetic test for congenital diseases at an affordable price.

Genetic diseases are diseases that arise in humans due to chromosomal mutations and defects in genes, that is, in the hereditary cellular apparatus. Damage to the genetic apparatus leads to serious and varied problems - hearing loss, visual impairment, delayed psycho-physical development, infertility and many other diseases.

The concept of chromosomes

Each cell of the body has a cell nucleus, the main part of which is made up of chromosomes. A set of 46 chromosomes is a karyotype. 22 pairs of chromosomes are autosomes, and the last 23 pair are sex chromosomes. These are the sex chromosomes that differentiate a man and a woman from each other.

Everyone knows that women have XX chromosomes, and men have XY chromosomes. When a new life arises, the mother passes on the X chromosome, and the father - either X or Y. It is with these chromosomes, or rather with their pathology, that genetic diseases are associated.

The gene can mutate. If it is recessive, then the mutation can be passed on from generation to generation without manifesting itself in any way. If the mutation is dominant, then it will definitely manifest itself, so it is advisable to protect your family by learning about the potential problem in time.

Genetic diseases are a problem in the modern world.

More and more hereditary pathologies are being discovered every year. More than 6,000 names of genetic diseases are already known; they are associated with both quantitative and qualitative changes in the genetic material. According to the World Health Organization, approximately 6% of children suffer from hereditary diseases.

The most unpleasant thing is that genetic diseases can appear only after several years. Parents rejoice at a healthy baby, not suspecting that their children are sick. For example, some hereditary diseases can manifest themselves at the age when the patient himself has children. And half of these children may be doomed if the parent carries a dominant pathological gene.

But sometimes it is enough to know that the child’s body is not able to absorb a certain element. If parents are warned about this in time, then in the future, simply avoiding products containing this component, you can protect the body from manifestations of a genetic disease.

Therefore, it is very important that when planning a pregnancy, a test for genetic diseases is done. If the test shows the likelihood of transmitting the mutated gene to the unborn child, then in German clinics they can carry out gene correction during artificial insemination. Tests can also be done during pregnancy.

In Germany, you can be offered innovative technologies of the latest diagnostic developments that can dispel all your doubts and suspicions. About 1,000 genetic diseases can be detected before a child is born.

Genetic diseases - what are the types?

We will look at two groups of genetic diseases (actually there are more)

1. Diseases with a genetic predisposition.

Such diseases can manifest themselves under the influence of external environmental factors and are very dependent on individual genetic predisposition. Some diseases may appear in older people, while others may appear unexpectedly and early. So, for example, a strong blow to the head can provoke epilepsy, taking an indigestible product can cause severe allergies, etc.

2. Diseases that develop in the presence of a dominant pathological gene.

Such genetic diseases are passed on from generation to generation. For example, muscular dystrophy, hemophilia, six-fingered, phenylketonuria.

Families at high risk of having a child with a genetic disease.

Which families first need to attend genetic consultations and identify the risk of hereditary diseases in their offspring?

1. Consanguineous marriages.

2. Infertility of unknown etiology.

3. Age of parents. It is considered a risk factor if the expectant mother is over 35 years old and the father is over 40 (according to some sources, over 45). With age, more and more damage appears in the reproductive cells, which increases the risk of having a baby with a hereditary pathology.

4. Hereditary family diseases, that is, similar diseases in two or more family members. There are diseases with pronounced symptoms and the parents have no doubt that this is a hereditary disease. But there are signs (microanomalies) that parents do not pay due attention to. For example, an unusual shape of the eyelids and ears, ptosis, coffee-colored spots on the skin, a strange smell of urine, sweat, etc.

5. Complicated obstetric history - stillbirth, more than one spontaneous miscarriage, missed pregnancies.

6. Parents are representatives of a small nationality or come from one small locality (in this case, there is a high probability of consanguineous marriages)

7. The impact of unfavorable household or professional factors on one of the parents (calcium deficiency, insufficient protein nutrition, work in a printing house, etc.)

8. Poor environmental conditions.

9. Use of drugs with teratogenic properties during pregnancy.

10. Diseases, especially viral etiology (rubella, chicken pox), suffered by a pregnant woman.

11. Unhealthy lifestyle. Constant stress, alcohol, smoking, drugs, poor nutrition can cause damage to genes, since the structure of chromosomes under the influence of unfavorable conditions can change throughout life.

Genetic diseases - what are the diagnostic methods?

In Germany, the diagnosis of genetic diseases is highly effective, since all known high-tech methods and absolutely all the capabilities of modern medicine (DNA analysis, DNA sequencing, genetic passport, etc.) are used to determine potential hereditary problems. Let's look at the most common ones.

1. Clinical and genealogical method.

This method is an important condition for high-quality diagnosis of a genetic disease. What does it include? First of all, a detailed interview with the patient. If there is a suspicion of a hereditary disease, then the survey concerns not only the parents themselves, but also all relatives, that is, complete and thorough information is collected about each family member. Subsequently, a pedigree is compiled indicating all the signs and diseases. This method ends with a genetic analysis, on the basis of which a correct diagnosis is made and optimal therapy is selected.

2. Cytogenetic method.

Thanks to this method, diseases that arise due to problems in the cell's chromosomes are determined. The cytogenetic method examines the internal structure and arrangement of chromosomes. This is a very simple technique - a scraping is taken from the mucous membrane of the inner surface of the cheek, then the scraping is examined under a microscope. This method is carried out with parents and family members. A type of cytogenetic method is molecular cytogenetic, which allows you to see the smallest changes in the structure of chromosomes.

3. Biochemical method.

This method, by examining the mother’s biological fluids (blood, saliva, sweat, urine, etc.), can determine hereditary diseases based on metabolic disorders. One of the most famous genetic diseases associated with metabolic disorders is albinism.

4. Molecular genetic method.

This is the most progressive method currently used to identify monogenic diseases. It is very accurate and detects pathology even in the nucleotide sequence. Thanks to this method, it is possible to determine a genetic predisposition to the development of oncology (cancer of the stomach, uterus, thyroid gland, prostate, leukemia, etc.) Therefore, it is especially indicated for persons whose close relatives suffered from endocrine, mental, oncological and vascular diseases.

In Germany, to diagnose genetic diseases, you will be offered the full range of cytogenetic, biochemical, molecular genetic studies, prenatal and postnatal diagnostics, plus neonatal screening of the newborn. Here you can take about 1,000 genetic tests that are approved for clinical use in the country.

Pregnancy and genetic diseases

Prenatal diagnosis provides great opportunities for identifying genetic diseases.

Prenatal diagnosis includes studies such as

• chorionic villus biopsy - analysis of fetal chorionic tissue at 7-9 weeks of pregnancy; a biopsy can be performed in two ways - through the cervix or by puncturing the anterior abdominal wall;
• amniocentesis - at 16-20 weeks of pregnancy, amniotic fluid is obtained through puncture of the anterior abdominal wall;
• Cordocentesis is one of the most important diagnostic methods, as it examines fetal blood obtained from the umbilical cord.

Screening methods such as triple test, fetal echocardiography, and determination of alpha-fetoprotein are also used in diagnosis.

Ultrasound imaging of the fetus in 3D and 4D dimensions can significantly reduce the birth of babies with developmental defects. All these methods have a low risk of side effects and do not adversely affect the course of pregnancy. If a genetic disease is detected during pregnancy, the doctor will suggest certain individual tactics for managing the pregnant woman. In the early stages of pregnancy, German clinics can offer gene correction. If gene correction is carried out in time in the embryonic period, then some genetic defects can be corrected.

Neonatal screening of a child in Germany

Neonatal newborn screening identifies the most common genetic diseases in an infant. Early diagnosis makes it possible to understand that a child is sick even before the first signs of illness appear. Thus, the following hereditary diseases can be identified - hypothyroidism, phenylketonuria, maple syrup disease, adrenogenital syndrome and others.

If these diseases are detected in time, the chance of curing them is quite high. High-quality neonatal screening is also one of the reasons why women fly to Germany to give birth to a child here.

Treatment of human genetic diseases in Germany

Until recently, genetic diseases were not treated; it was considered impossible, and therefore hopeless. Therefore, the diagnosis of a genetic disease was regarded as a death sentence, and at best, one could only count on symptomatic treatment. Now the situation has changed. Progress is noticeable, positive treatment results have appeared, and what’s more, science is constantly discovering new and effective ways to treat hereditary diseases. And although many hereditary diseases cannot be cured today, geneticists are optimistic about the future.

Treatment of genetic diseases is a very complex process. It is based on the same principles of influence as any other disease - etiological, pathogenetic and symptomatic. Let's look briefly at each.

1. Etiological principle of influence.

The etiological principle of influence is the most optimal, since treatment is aimed directly at the causes of the disease. This is achieved using methods of gene correction, isolating the damaged part of DNA, cloning it and introducing it into the body. At the moment, this task is very difficult, but for some diseases it is already feasible

2. Pathogenetic principle of influence.

Treatment is aimed at the mechanism of development of the disease, that is, it changes the physiological and biochemical processes in the body, eliminating defects caused by the pathological gene. As genetics develops, the pathogenetic principle of influence expands, and for different diseases, new ways and possibilities for correcting damaged links will be found every year.

3. Symptomatic principle of influence.

According to this principle, treatment of a genetic disease is aimed at relieving pain and other unpleasant phenomena and preventing further progression of the disease. Symptomatic treatment is always prescribed; it can be combined with other methods of treatment, or it can be an independent and sole treatment. This is the prescription of painkillers, sedatives, anticonvulsants and other medications. The pharmacological industry is now very developed, so the range of drugs used to treat (or rather, to alleviate the manifestations of) genetic diseases is very wide.

In addition to drug treatment, symptomatic treatment includes the use of physiotherapeutic procedures - massage, inhalations, electrotherapy, balneotherapy, etc.

Sometimes surgical treatment is used to correct deformities, both external and internal.

Geneticists in Germany already have extensive experience in treating genetic diseases. Depending on the manifestation of the disease and individual parameters, the following approaches are used:

• genetic nutrition;
• gene therapy,
• stem cell transplantation,
• organ and tissue transplantation,
• enzyme therapy,
• hormone and enzyme replacement therapy;
• hemosorption, plasmaphoresis, lymphosorption - cleansing the body with special preparations;
• surgery.

Of course, treatment of genetic diseases takes a long time and is not always successful. But the number of new approaches to therapy is growing every year, so doctors are optimistic.

Gene therapy

Doctors and scientists around the world place special hopes on gene therapy, thanks to which it is possible to introduce high-quality genetic material into the cells of a sick organism.

Gene correction consists of the following stages:

• obtaining genetic material (somatic cells) from the patient;
• introduction of a therapeutic gene into this material, which corrects the gene defect;
• cloning of corrected cells;
• introduction of new healthy cells into the patient’s body.

Gene correction requires great caution, since science does not yet have complete information about the functioning of the genetic apparatus.

List of genetic diseases that can be identified

There are many classifications of genetic diseases, they are arbitrary and differ in the principle of construction. Below we provide a list of the most common genetic and hereditary diseases:

• Gunther's disease;
• Canavan disease;
• Niemann-Pick disease;
• Tay-Sachs disease;
• Charcot-Marie disease;
• hemophilia;
• hypertrichosis;
• color blindness - insensitivity to color, color blindness is transmitted only with the female chromosome, but the disease affects only men;
• Capgras fallacy;
• Pelizaeus-Merzbacher leukodystrophy;
• Blashko lines;
• micropsia;
• cystic fibrosis;
• neurofibromatosis;
• heightened reflection;
• porphyria;
• progeria;
• spina bifida;
• Angelman syndrome;
• exploding head syndrome;
• blue skin syndrome;
• Down syndrome;
• living corpse syndrome;
• Joubert syndrome;
• stone man syndrome
• Klinefelter's syndrome;
• Klein-Levin syndrome;
• Martin-Bell syndrome;
• Marfan syndrome;
• Prader-Willi syndrome;
• Robin's syndrome;
• Stendhal's syndrome;
• Turner syndrome;
• elephantiasis;
• phenylketonuria.
• cicero and others.

In this section we will go into detail about each disease and tell you how some of them can be cured. But it is better to prevent genetic diseases than to treat them, especially since modern medicine does not know how to cure many diseases.

Genetic diseases are a group of diseases that are very heterogeneous in their clinical manifestations. The main external manifestations of genetic diseases:

• small head (microcephaly);
• microanomalies (“third eyelid”, short neck, unusually shaped ears, etc.)
• delayed physical and mental development;
• changes in genital organs;
• excessive muscle relaxation;
• change in the shape of the toes and hands;
• violation of psychological status, etc.

Genetic diseases - how to get advice in Germany?

Conversation in genetic consultation and prenatal diagnosis can prevent severe hereditary diseases transmitted at the gene level. The main goal of genetic counseling is to identify the degree of risk of a genetic disease in a newborn.

In order to receive quality consultation and advice on further actions, you need to be serious about communicating with your doctor. Before the consultation, you need to responsibly prepare for the conversation, remember the illnesses that your relatives suffered, describe all health problems and write down the main questions to which you would like to receive answers.

If the family already has a child with an anomaly, with congenital malformations, take his photographs. It is imperative to talk about spontaneous miscarriages, cases of stillbirth, and how the pregnancy went (is going).

A genetic consultation doctor will be able to calculate the risk of having a baby with a severe hereditary pathology (even in the future). When can we talk about a high risk of developing a genetic disease?

• a genetic risk of up to 5% is considered low;
• no more than 10% - slightly increased risk;
• from 10% to 20% - average risk;
• above 20% - high risk.

Doctors advise considering a risk of about or above 20% as a reason to terminate the pregnancy or (if one does not exist yet) as a contraindication to conception. But the final decision is made, of course, by the married couple.

The consultation may take place in several stages. When diagnosing a genetic disease in a woman, the doctor develops management tactics before pregnancy and, if necessary, during pregnancy. The doctor talks in detail about the course of the disease, life expectancy for this pathology, all the possibilities of modern therapy, the price component, and the prognosis of the disease. Sometimes gene correction during artificial insemination or during embryonic development allows one to avoid the manifestations of the disease. Every year, new methods of gene therapy and the prevention of hereditary diseases are being developed, so the chances of curing genetic pathology are constantly increasing.

In Germany, methods of combating gene mutations using stem cells are being actively introduced and are already being successfully applied, and new technologies are being considered for the treatment and diagnosis of genetic diseases.

Hereditary diseases are diseases whose development is caused by certain gene and chromosomal mutations. Quite often, terms such as “hereditary diseases” and “congenital diseases” are confused, which can also be used as synonyms.

Congenital diseases include those diseases that are present at the birth of a child, and their development can be provoked not only by hereditary factors, but also by exogenous ones.

For example, these may include heart defects, which may be associated with negative effects on the child of chemical compounds, ionizing radiation, various medications that a woman takes during pregnancy, and of course, the presence of various intrauterine infections.

At the same time, not all hereditary diseases will be classified as congenital, because many of them can begin to appear after the neonatal period (for example, after 40 years, Huntington's chorea can be detected).

In almost 30% of cases, hospitalization of children occurs due to congenital and hereditary diseases. In this case, the unstudied nature of a particular disease will be of greatest importance, which may largely be due to the presence of genetic factors.

Hereditary diseases can also have such a synonym as “family diseases”, because the onset of their development is most often determined not only by certain hereditary factors, but also by the professional or national traditions of the family, and of course, by the living conditions of a person.

Taking into account the exact relationship between exogenous and hereditary factors, pathogenesis and etiology in the development of a particular disease, all human diseases can be conditionally divided into exactly three categories:

• The 1st category is those hereditary diseases that manifest themselves taking into account a pathological mutation as an etiological factor, which will practically not depend on environmental influences, since in this case it will be determined only as the degree of severity of certain signs of the disease itself. The 1st category of hereditary diseases will include all gene and chromosomal diseases characterized by full manifestation (for example, these will include, etc.);
• The 2nd category is those diseases that are called multifactorial diseases. That is, the basis of their development lies precisely in the interaction of environmental and genetic factors. This category of hereditary diseases will include diseases such as peptic ulcer of the duodenum and stomach, various allergic diseases, as well as various malformations and some forms of obesity.

The presence of genetic factors, which appear to be a characteristic polygenic system, will be determined by a genetic predisposition, while the onset of its implementation may occur in the event of exposure to harmful or unfavorable environmental factors (for example, mental or physical fatigue, violation of a balanced and rational diet, disruption of the usual regime and etc.). Moreover, for one category of people such an influence will be less important, and for others it will be greater.

Multifactorial diseases will also include certain conditions in which only one mutant gene will play the main role of a genetic factor. However, this condition manifests itself only under certain favorable conditions (for example, such a condition can manifest itself with dehydrogenase, that is, a deficiency of glucose-6-phosphate);

• Category 3 - these are certain diseases, the onset of development of which is directly related to exposure to harmful or negative environmental factors, while the presence of heredity will play virtually no significance. This category includes burns, injuries, and acute infectious diseases. But, at the same time, the course of the disease itself can be directly influenced by certain genetic factors (for example, on the speed of recovery, the development of decompensation of the function of injured organs, the transition from an acute to a chronic form, etc.). Most often, hereditary diseases will be divided into three main groups - monogenic, chromosomal and polygenic (that is, diseases with a hereditary predisposition or multifactorial).

Classification of hereditary diseases

The clinical classification of diseases is based on the systemic and organ principle. Taking into account this classification, hereditary diseases are divided into the endocrine, nervous, cardiovascular and respiratory systems. As well as the gastrointestinal tract, liver, blood systems, kidneys, eyes, ears, skin, etc.

At the same time, this classification is conditional, because most hereditary diseases will be characterized by the involvement of systemic tissue damage or several organs in the pathological process itself.

According to the type of inheritance, monogenic diseases can be autosomal recessive, autosomal dominant, or sex-linked. Taking into account the phenotypic manifestation - fermentopathies, that is, metabolic diseases, which include diseases with impaired DNA repair. Phenotypic manifestations include immunopathology (also diseases that were provoked by disorders in the complement system), pathologies of the blood coagulation system, disorders of the synthesis of peptide hormones and transport proteins.

Monogenic diseases will also include a group of syndromes that have a large number of congenital malformations, in the presence of which the primary defect of the mutant gene will not be specified. All monogenic diseases will be inherited from parents, taking into account all Mendelian laws.

Most of the hereditary diseases known to science are caused precisely by mutations of structural genes, while today there is still indirect evidence and probability of the etiological role of mutations of regulatory genes in a certain category of diseases.

For diseases, the development of which is based on a violation of the correct synthesis of proteins or structural proteins that perform certain specific functions (for example, hemoglobin), an autosomal dominant type of inheritance is characteristic.

In the case of an autosomal dominant type of inheritance, the effect of the mutant gene will manifest itself in almost all cases. The birth of both sick girls and sick boys occurs with the same frequency. At the same time, the probability of developing the disease in the offspring is approximately 50%. If a mutation develops again in the gamete of one of the parents, then a sporadic case of dominant pathology may occur. This type of inheritance can transmit Albright's disease, otosclerosis, dysostosis, thalassemia, paroxysmal myoplegia, etc.

In the case of an autosomal recessive type of inheritance, the mutant gene itself will manifest itself exclusively in the homozygous state. In this case, sick girls and boys are born equally. The rate of birth of a sick baby is approximately 20%. In this case, a sick child can also be born to phenotopically healthy parents, who at the same time are carriers of the mutant gene.

The most characteristic is the autosomal recessive type of inheritance of diseases for those diseases, the development of which will disrupt the functions of several or one enzyme, which is called fermentopathy.

The basis of recessive inheritance, which is linked to the X chromosome, is precisely the effect of a mutant gene, the manifestation of which occurs exclusively with the XY set of sex chromosomes, therefore, in boys. There is approximately a 50% chance that a mother who is a carrier of the mutant gene will have a sick boy. The girls born will be practically healthy, while some of them will act as carriers of the mutant gene, which may also be called “conductors”.

Dominant inheritance, which is linked to the X chromosome, is based on the influence of a dominant mutant gene, which can manifest itself in the presence of absolutely any set of sex chromosomes. Such diseases will be most severe in boys. A sick man with this type of inheritance will have all his sons completely healthy, but his daughters will be born affected. In the future, sick women are able to pass on the altered gene to their daughters and sons.

As a result of a gene mutation, a disruption in the correct synthesis of proteins that perform structural or plastic functions may occur. The most likely reason for the onset of the development of diseases such as osteogenesis imperfecta and osteodysplasia is precisely the disruption of the synthesis of structural proteins.

Today, there is evidence that such disorders play an important role in the pathogenesis of hereditary nephritis-like diseases (familial hematuria, Alport syndrome). As a result of abnormalities in the structure of proteins, tissue dysplasia can be observed both in the kidneys and in any other organs. It is the pathology of structural proteins that is characteristic of most hereditary diseases that have an autosomal dominant type of inheritance.

As a result of a gene mutation, the development of diseases that are provoked by immunodeficiency conditions can occur. Agammaglobulinemia will be quite difficult, especially if combined with thymic aplasia.

The main reason for the formation of hemoglobin, which has an abnormal structure in sickle cell anemia, will be the replacement of glutamic acid residues in its molecules with a vanillin residue. It is this replacement that is the result of a gene mutation that has occurred. As a result of achieving this discovery, a more detailed study of a fairly large group of hereditary diseases that can be provoked was laid.

To date, scientists have identified a number of mutant genes that control the synthesis of blood clotting factors. As a result of genetically determined disturbances in the synthesis of antihemophilic globulin, the development may begin. If there is a violation in the synthesis of the thromboplastic component, the development of hemophilia B begins. And as a result of the lack of the precursor thromboplastin, the basis for the pathogenesis of hemophilia C is found.

It is as a result of gene mutations that have occurred that a disruption can occur in the mechanism of transport of various compounds through cell membranes. To date, the most studied are hereditary pathologies of amino acid transport in the kidneys and intestines.

Multifactorial or polygenic hereditary diseases, or diseases that have a hereditary predisposition, are based on the interaction of several genes at once, both in polygenic systems and environmental factors. Despite the fact that diseases with a hereditary predisposition are quite common today, they are still poorly understood.

Only an experienced specialist can tell you about the likelihood of a child inheriting a particular disease.

The manifestation of certain hereditary diseases in humans, according to scientists, is associated with several reasons:

• change in the number of chromosomes;
• disturbances in the structure of the parents' chromosomes;
• mutations at the gene level.

Of the total, only one pair contains sex chromosomes, and all the rest are autosomal and differ from each other in size and shape. A healthy person has 23 chromosome pairs. The appearance of an extra chromosome or its disappearance causes various constitutional changes in the human body.

As a result of the development of modern science, scientists have not only counted the chromosomes, but can now recognize each pair. Carrying out karyotype analyzes allows us to identify the existence of a hereditary disease in the early stages of a person’s life. These changes are associated with an imbalance of a specific chromosome pair.

Causes of hereditary diseases

Causes of hereditary diseases, associated with hereditary causes, can be divided into several groups:

• diseases of direct effect or congenital; they appear in the child immediately after birth. Typical representatives include hemophilia, phenylketonuria, and Down's disease. Scientists directly associate the occurrence of such diseases with the lifestyle and living conditions that both parents lived before getting married and conceiving a child. Often the cause of the development of this type of pathology is the lifestyle of the expectant mother during pregnancy. Most often, among the reasons contributing to changes in the set of chromosomes are the use of alcoholic beverages, drug-containing substances, and negative environmental conditions.
• diseases that are inherited from parents, but activated by sudden exposure to external stimuli. Such diseases progress during the growth and development of the child; their occurrence and further expansion will provoke the negativity of the mechanisms responsible for heredity. The main factor triggering the increase in symptoms is a socially negative lifestyle. Most often, such factors can cause diabetes and mental disorders.
• diseases directly related to inherited predisposition. In the presence of serious factors associated with external conditions, bronchial asthma, atherosclerosis, some heart diseases, ulcers, etc. may develop. Harmful factors include poor quality nutrition, negative ecology, thoughtless medication, and constant use of household chemicals.

Chromosomal hereditary changes

Mutations associated with changes in the number of chromosomes look like a violation of the division process - meiosis. As a result of a failure in the “program,” duplication of existing pairs of chromosomes, both sex and somatic, occurs. Sex-dependent hereditary abnormalities are transmitted via the sex X chromosome.

In the male body, this chromosome is found without a pair, thereby preserving the manifestation of a hereditary disease in men. There is a pair of “X” in the female body, so women are considered carriers of a low-quality X chromosome. In order to chromosomal hereditary diseases transmitted exclusively through the female line, the presence of an anomalous pair is necessary. This effect is quite rare in nature.

Genetic hereditary diseases

Most hereditary diseases occur as a result of gene mutations, which are changes in DNA at the molecular level and are well known to genetic scientists and pediatricians. There are gene mutations that manifest themselves at the molecular, cellular, tissue or organ levels. Despite the fact that the gap from mutation at the level of DNA molecules to the main phenotype is large, it must be emphasized that all possible mutations in tissues, organs and cells of the body belong to the phenotype. Although they are purely external changes.

Among other things, one should not lose sight of the possibility of the dangerous influence of ecology and other genes that cause various modifications and implement the functions of mutating genes. The multiple forms of proteins, the diversity of their functions and the lack of scientific knowledge in the field of metabolic processes negatively affect attempts to create a classification of gene diseases.

Conclusion

Modern medicine has about 5500-6500 clinical forms of gene diseases. These data are indicative due to the lack of clear boundaries when separating individual forms. Some genetic hereditary diseases represent different forms from a clinical point of view, but from a genetic point of view they are the consequences of a mutation in one locus.

Hereditary diseases are diseases caused by chromosomal and gene mutations. The science that studies the phenomena of heredity and variability in human populations is genetics. It is often believed that the terms “hereditary disease” and “congenital disease” are synonymous. However, unlike congenital diseases that occur at the birth of a child, hereditary diseases are already caused by hereditary and exogenous factors.

Problems of heredity have interested people for many centuries. For example, such a disease as hemophilia has been known for a long time. In this regard, marriages between blood relatives were prohibited. Many scientists have put forward their hypotheses about the occurrence of hereditary pathologies. Their assumptions were not always based on scientific observations. Only in the 20th century, with the development of genetics, scientific evidence was revealed.

Progress in the medical field has led to a relative increase in the proportion of genetically determined pathologies. To date, more than 3,500 hereditary human diseases have been identified. About 5% of children are born with genetic or congenital diseases.

From a genetic point of view, all diseases with hereditary and environmental factors in their development can be divided into 3 groups:

1. Hereditary diseases with a phenotypic mutation that are almost independent of the environment. These are, as a rule, genetic and chromosomal hereditary diseases, such as hemophilia, Down's disease, phenylketonuria and others.
2. Diseases with a hereditary predisposition, the manifestation of which requires the influence of the external environment. Among such diseases are diabetes mellitus, gout, atherosclerosis, peptic ulcer, psoriasis, hypertension, etc.
3. Diseases in the origin of which heredity does not play a role. These include injuries, burns, and any infectious diseases.

Diseases caused by changes in the structure of chromosomes are called chromosomal diseases. Diseases caused by changes in DNA structure are called gene diseases. Clinical diagnosis of hereditary diseases is based on clinical, genealogical and paraclinical examination.

It should be noted that until recently, almost all hereditary diseases were considered incurable. However, today everything has changed. By diagnosing diseases in the early stages, I can alleviate people’s suffering, and sometimes even get rid of the disease. Thanks to genetics, today there are many express diagnostic methods, for example, biochemical tests and immunological methods. A clear example is the ability of modern medicine to fight the disease polio.