Human genetic diseases briefly. Hereditary diseases - their causes

Zhitikhina Marina

This paper describes the causes and measures to prevent hereditary diseases in the village of Sosnovo-Ozerskoye

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Ministry of Education and Science of the Republic of Belarus

Municipal municipality "Eravninsky district"

MBOU "Sosnovo-Ozersk Secondary School No. 2"

Regional scientific and practical conference “Step into the future”

Section: biology

Causes and prevention of hereditary diseases

student of grade 9a, MBOU "Sosnovo-Ozerskaya Secondary School No. 2"

Supervisor: Tsyrendorzhieva Natalia Nikolaevna,

Biology teacher MBOU "Sosnovo-Ozerskaya Secondary School No. 2"

2017

1. Introduction ___________________________________________________2
2. Main part

1. Classification of hereditary diseases_______________________________________________3-8
2. Risk factors for hereditary diseases_____________8-9
3. Prevention measures _________________________________9-10
4. Family planning as a method of preventing hereditary diseases________________________________________________10-11
5. The situation of hereditary diseases in the village of Sosnovo-Ozerskoye. Survey results _____________________________11-12

1. Conclusion _____________________________________________ 12-13
2. Used literature________________________________14

1. Introduction

In biology classes, I studied with interest the basics of genetic knowledge, mastered problem-solving skills, analysis and forecasting. I was especially interested in human genetics: hereditary diseases, the causes of their occurrence, the possibility of prevention and treatment.

The word “inheritance” creates the illusion that all diseases studied by genetics are passed on from parents to children, as if from hand to hand: what the grandfathers were sick with, the fathers will be sick with, and then the grandchildren. I asked myself: “Is this really what happens?”

Genetics is fundamentally the science of heredity. It deals with the phenomena of heredity that were explained by Mendel and his closest followers.

Relevance. A very important problem is the study of the laws according to which diseases and various defects are inherited in humans. In some cases, basic knowledge of genetics helps people figure out if they are dealing with inherited defects. Knowledge of the basics of genetics gives confidence to people suffering from ailments that are not inherited, that their children will not experience similar suffering.

In this work it is set target – research into the causes of hereditary diseases. And also their prevention. Considering that this problem is widely studied in modern science and concerns many questions, the following questions have been posed: tasks:

• study of the classification and causes of hereditary diseases;
• get acquainted with risk factors and measures to prevent hereditary human diseases;
• determining the value of genetic research for the prevention and treatment of hereditary diseases.;
• conduct a survey among classmates.

1. Main part

1. Classification of hereditary diseases

Nowadays, a lot of attention is paid to human genetics, and this is primarily due to the development of our civilizations, with the fact that as a result of this, many factors appear in the environment surrounding a person that negatively affect his heredity, as a result of which mutations can occur, that is, changes in the genetic information of a cell.

Science still does not know all the hereditary diseases that occur in humans. Apparently, their number can reach 40 thousand, but scientists have discovered only 1/6 of this number. Apparently, this is due to the fact that many cases of genetic pathology are harmless and can be successfully treated, which is why doctors consider them non-hereditary. You should know that serious and severe hereditary diseases are relatively rare, usually the ratio is as follows: 1 sick person per 10 thousand people or more. This means that there is no need to panic in advance due to unfounded suspicions: nature carefully protects the genetic health of humanity.

Hereditary human diseases can be classified as follows:

1. Genetic diseases.They arise as a result of DNA damage at the gene level. These diseases include Niemann-Pick disease and phenylketonuria.
2. Chromosomal diseases . Diseases associated with an abnormality in the number of chromosomes or a violation of their structure. Examples of chromosomal disorders are Down syndrome, Klinefelter syndrome, and Patau syndrome.
3. Diseases with hereditary predisposition (hypertension , diabetes mellitus, rheumatism, schizophrenia, coronary heart disease).

The complexity and diversity of metabolic processes, the number of enzymes and the incompleteness of scientific data on their functions in the human body still do not allow the creation of a holistic classification of hereditary diseases.

First of all, you should learn to distinguish diseases defined as congenital from real hereditary diseases. Congenital is a disease that a person has from the moment of birth. As soon as a little person is born who is unlucky with his health, doctors can diagnose him with a congenital ailment, unless nothing misleads them.

The situation is different with hereditary diseases. Some of them are truly congenital, i.e. accompany a person from the moment of his first breath. But there are also those that appear only a few years after birth. Everyone is well aware of Alzheimer's disease, which leads to senile insanity and is a terrible threat for older people. Alzheimer's disease appears only in very old and even elderly people and is never observed in young people. Meanwhile, this is a hereditary disease. The defective gene is present in a person from the moment of birth, but for decades it seems to lie dormant.

Not all hereditary diseases are congenital, and not all congenital diseases are hereditary. There are many pathologies that a person suffers from from the moment he is born, but which were not passed on to him from his parents.

Gene diseases

A gene disorder occurs when a person has a harmful mutation at the gene level.

This means that a small section of the DNA molecule encoding some substance or control has undergone undesirable changes.

some kind of biochemical process. It is known that gene diseases are easily transmitted from generation to generation, and this occurs exactly according to the classical Mendelian scheme.

They are implemented regardless of whether environmental conditions are conducive to maintaining health or not. Only when the defective gene is identified can it be determined what kind of lifestyle to lead in order to feel strong and healthy, successfully resisting the disease. In some cases, genetic defects are very strong and sharply reduce a person’s chances of recovery.

The clinical manifestations of genetic diseases are varied; no common symptoms have been found for all or at least most of them, except for those features that mark all hereditary diseases.

It is known that for one gene the number of mutations can reach up to 1000. But this number is the maximum that few genes are capable of. Therefore, it is better to take the average value of 200 changes per 1 gene. It is clear that the number of diseases should be much less than the number of mutations. In addition, the cells have an effective protective mechanism that eliminates genetic defects.

Initially, doctors believed that any mutation of 1 gene leads to only one disease, but then it turned out that this was incorrect. Some mutations of the same gene can lead to different diseases, especially if they are localized in different parts of the gene. Sometimes mutations affect only part of the cells. This means that some human cells have a healthy form of the gene, while others have a defective form. If the mutation is weak, then most people will not show it. If the mutation is strong, then the disease will develop, but will be mild. Such “weakening” forms of the disease are called mosaic; they account for 10% of gene diseases.

Many diseases with this type of inheritance affect reproductive abilities. These diseases are dangerous because they are complicated by mutations in subsequent generations. Weak mutations are inherited in much the same way as strong ones, but far from being manifested in all descendants.

Chromosomal diseases

Chromosomal diseases, despite the relatively infrequent occurrence, are very numerous. To date, 1000 varieties of chromosomal pathology have been identified, of which 100 forms are described in sufficient detail and received the status of syndromes in medicine.

A balanced set of genes leads to deviations in the development of the organism. Often this effect results in intrauterine death of the embryo (or fetus).

In many chromosomal diseases, there is a clear relationship between deviations from normal development and the degree of chromosomal imbalance. The more chromosomal material is affected by the anomaly, the earlier it is possible to observe the signs of the disease and the more severe the disturbances in physical and mental development manifest themselves.

Diseases with a hereditary predisposition

They differ from gene diseases in that for their manifestation they need the action of environmental factors and represent the most extensive group of hereditary pathology and are very diverse. All this is due to the involvement of many genes (polygenic systems) and their complex interaction with environmental factors during the development of the disease. In this regard, this group is sometimes called multifactorial diseases. Even for the same disease, the relative importance of heredity and environment may vary from person to person. By genetic nature, these are two groups of diseases.

Monogenic diseases with hereditary predisposition- predisposition is associated with a pathological mutation of one gene. For its manifestation, predisposition requires the obligatory action of an external environmental factor, which is usually identified and can be considered as specific in relation to a given disease.

The terms "diseases with a hereditary predisposition" and "multifactorial diseases" mean the same thing. In Russian literature, the term multifactorial (or multifactorial) diseases is more often used.

Multifactorial diseases can occur in utero (congenital malformations) or at any age of postnatal development. At the same time, the older the individual, the more likely he is to develop a multifactorial disease. Unlike monogenic diseases, multifactorial diseases are common diseases. Most multifactorial diseases are polygenic from a genetic point of view, i.e. several genes are involved in their formation.

Congenital malformations, such as cleft lip and palate, anencephaly, hydrocephalus, clubfoot, hip dislocation and others, are formed in utero at the time of birth and, as a rule, are diagnosed in the earliest periods of postnatal ontogenesis. Their development is the result of the interaction of numerous genetic factors with adverse maternal or environmental factors (teratogens) during fetal development. They are found in human populations for each nosological form infrequently, but in total - in 3-5% of the population.

Mental and nervous diseases, as well as somatic diseases, belonging to the group of multifactorial diseases, are polygenic (genetically heterogeneous), but develop in interaction with environmental factors in the postnatal period of ontogenesis in adult individuals. This group refers to socially significant common diseases:cardiovascular (myocardial infarction, arterial hypertension, stroke), bronchopulmonary (bronchial asthma, chronic obstructive pulmonary diseases), mental (schizophrenia, bipolar psychosis), malignant neoplasms, infectious diseases, etc.

1. Risk factors for hereditary diseases

1. Physical factors(various types of ionizing radiation, ultraviolet radiation).
2. Chemical factors(insecticides, herbicides, drugs, alcohol, some medications and other substances).
3. Biological factors(smallpox, chickenpox, mumps, influenza, measles, hepatitis, etc. viruses).

For multifactorial diseases, the following scheme of the reasons for their development can be proposed:

The transmission of multifactorial diseases in families does not comply with Mendelian laws. The distribution of such diseases in families is fundamentally different from monogenic (Mendelian) diseases.

The risk of developing the disease in a child depends on the health of the parents. So, if one of the parents of a sick child also suffers from bronchial asthma, the probability of developing the disease in the child ranges from 20 to 30%; if both parents are sick, it reaches 75%. In general, it is believed that the risk of bronchial asthma in a child whose parents have signs of atopy is 2-3 times higher than in those families in which parents do not have these signs. When comparing the descendants of healthy people and the descendants of patients with bronchial asthma, it turned out that the risk for a child to get bronchial asthma is 2.6 times higher if the mother is sick, 2.5 times higher if the father is sick, and 6.7 times higher if Both parents are sick. In general, the genetic risk for relatives in relation to a monogenic pathology is usually higher than in the case of a multifactorial one.

1. Prevention and treatment of hereditary diseases

Prevention

There are four main methods for preventing human hereditary diseases, and to understand them in more detail, let's look at the diagram:

So, the first method of preventing hereditary diseases– this is genetic normalization and exclusion of mutagens. It is necessary to conduct a strict assessment of the mutagenic hazard of environmental factors, to exclude drugs that can cause mutation, food additives, as well as unfounded x-ray studies.

The second, one of the most important methods of preventionhereditary diseases - this is family planning, refusal to marry blood relatives, as well as refusal to bear children with a high risk of hereditary pathology. Timely medical and genetic counseling of married couples plays a huge role in this, which is now beginning to actively develop in our country.

Third method is a prenatal diagnosis using various physiological methods, that is, warning parents about possible pathologies in their unborn child.

Fourth Method – it is the control of the action of genes. Unfortunately, this is already the correction of hereditary diseases, most often metabolic diseases after birth. Diets, surgery, or drug therapy.

Treatment

Diet therapy; replacement therapy; removal of toxic metabolic products; mediator effect (on the synthesis of enzymes); exclusion of certain drugs (barbiturates, sulfonamides, etc.); surgery.

Treatment of hereditary diseases is extremely difficult; to be honest, it practically does not exist; you can only improve the symptoms. Therefore, the prevention of these diseases comes to the fore.

1. Family planning

Family planning includes all activities aimed at conceiving and giving birth to healthy and desired children. These activities include: preparation for a desired pregnancy, regulation of the interval between pregnancies, control of the timing of childbearing, control of the number of children in the family.

The age of parents trying to have a child is of great preventive importance. At some point, our body is too immature for this to grow full-fledged gametes. From a certain age, the body begins to age, the reason for which is the loss of its cells’ ability to divide normally. A preventive measure is to avoid childbearing before 19-21 years of age and after 30-35 years of age. Conceiving a child at an early age is dangerous mainly for the body of a young mother, but conceiving at a later age is more dangerous for the genetic health of the baby, as it leads to genetic, genomic and chromosomal mutations.

Monitoring includes non-invasive and invasive methods for prenatal diagnosis of diseases. The best way to examine the fetus today is ultrasound.

Repeated ultrasound is done with the following indications:

1) signs of pathology were revealed during screening ultrasound;

2) there are no signs of pathology, but the size of the fetus does not correspond to the duration of pregnancy.

3) the woman already has a child who has a congenital anomaly.

4) one of the parents has hereditary diseases.

5) if a pregnant woman was irradiated within 10 days or acquired a dangerous infection.

It is very important for a woman who is preparing to become a mother to remember the following things. Regardless of the desire to have a child of a certain gender, in no case should you sharply limit the consumption of fruits and animal proteins - this is extremely harmful to the health of the mother. And in addition, shortly before pregnancy, you should reduce your consumption of seafood. However, diet and genetics of a pregnant woman is a special subject of research by geneticists.

1. Disease situation in the village of Sosnovo-Ozerskoye

During my research, I found out that in our village of Sosnovo-Ozerskoye, diseases with a hereditary predisposition are mainly common. These are like:

1) oncological diseases (cancer);

2) diseases of the cardiovascular system (hypertension);

3) heart disease (heart disease);

4) diseases of the respiratory system (bronchial asthma);

5) diseases of the endocrine system (diabetes mellitus);

6) various allergic diseases.

Every year the birth rate of children with congenital hereditary diseases is growing, but this increase is insignificant.

I conducted a survey among students in my 9th grade. 20 people took part in the survey. Each student had to answer three questions:

1) What do you know about your heredity?

2) Is it possible to avoid hereditary diseases?

3) What measures to prevent hereditary diseases do you know?

The test result showed that little is known about the concept of “heredity”. Just what we learned in biology class. And the test results are as follows:

1. 15 (75%) people said they knew almost nothing about their heredity; 5 (25%) people answered that their heredity is good.
2. Everyone (100%) answered the second question that hereditary diseases cannot be avoided, because they are inherited.
3. 12 (60%) people answered that it is necessary to lead a healthy lifestyle, 3 (15%) girls answered that it is necessary to plan to have children in the future, and 5 people found it difficult to answer the third question.

Based on the results of my research, I did conclusion, that the topic of heredity is very relevant. Wider study of this topic is needed. I'm glad to see how my classmates answered the third question about prevention. Yes, it is necessary to lead a healthy lifestyle, especially for pregnant women. Conduct prevention of smoking, drug addiction and drunkenness. It is also necessary to plan a family and the birth of future children. Pregnant women need to consult a geneticist.

1. Conclusion

Now I know that it is possible to inherit something unpleasant hidden in our genes - hereditary diseases that become a heavy burden for the patient himself and for his loved ones.

Whether it is diabetes mellitus, Alzheimer's disease or pathology of the cardiovascular system, the presence of hereditary diseases in the family leaves its mark on a person's life. Some try to ignore it, while others are obsessed with their family's medical history and genetics. But in any case, it is not easy to live with the question: “Will you comprehendWill I have the same fate?

The presence of hereditary diseases in a family often causes anxiety and concern. This can interfere with quality of life.

In their practice, genetic counselors encounter many people who consider themselves genetically doomed. Their job is to help patients understand their possible risk of developing inherited diseases.

Heart disease and many types of cancer do not have a clearly defined cause. Instead, they are the result of a combination of genetic factors, environment and lifestyle. Genetic predisposition to the disease is just one of the risk factors, like smoking or a sedentary lifestyle.

The results of my research confirm that hereditary predisposition does not always mean disease.

It is important to understand that a person is not born with a genetically predetermined fate, and human health largely depends on our lifestyle.

1. List of used literature

1. Pimenova I.N., Pimenov A.V. Lectures on general biology: Textbook. - Saratov: Lyceum, 2003.
2. Pugacheva T.N., Heredity and health. - Series “Family Medical Encyclopedia”, World of Books, Moscow, 2007.
3. Karuzina I.P. Biology. - M.: Medicine, 1972.
4. Lobashev M.E. Genetics-L.: Publishing house of Leningrad University, 1967
5. Krestyaninov V.Yu., Vainer G.B. Collection of problems on genetics - Saratov: Lyceum, 1998.

Hereditary diseases pediatricians, neurologists, endocrinologists

A-Z A B C D E F G H I J J K L M N O P R S T U V X C CH W SCH E Y Z All sections Hereditary diseases Emergency conditions Eye diseases Children's diseases Men's diseases Venereal diseases Women's diseases Skin diseases Infectious diseases Nervous diseases Rheumatic diseases Urological diseases Endocrine diseases Immune diseases Allergic diseases Oncological diseases Diseases of the veins and lymph nodes Hair diseases Dental diseases Blood diseases Breast diseases ODS diseases and injuries Respiratory diseases Diseases of the digestive system Diseases of the heart and blood vessels Diseases of the large intestine Diseases of the ear, throat , nose Drug problems Mental disorders Speech disorders Cosmetic problems Aesthetic problems

Hereditary diseases– a large group of human diseases caused by pathological changes in the genetic apparatus. Currently, more than 6 thousand syndromes with a hereditary transmission mechanism are known, and their overall frequency in the population ranges from 0.2 to 4%. Some genetic diseases have a specific ethnic and geographic prevalence, while others occur with equal frequency throughout the world. The study of hereditary diseases is primarily the responsibility of medical genetics, but almost any medical specialist can encounter such a pathology: pediatricians, neurologists, endocrinologists, hematologists, therapists, etc.

Hereditary diseases should be distinguished from congenital and family pathologies. Congenital diseases can be caused not only by genetics, but also by unfavorable exogenous factors affecting the developing fetus (chemical and medicinal compounds, ionizing radiation, intrauterine infections, etc.). At the same time, not all hereditary diseases appear immediately after birth: for example, signs of Huntington's chorea usually first appear at the age of over 40 years. The difference between hereditary and family pathology is that the latter may be associated not with genetic, but with social, everyday or professional determinants.

The occurrence of hereditary diseases is caused by mutations - sudden changes in the genetic properties of an individual, leading to the appearance of new, unusual characteristics. If mutations affect individual chromosomes, changing their structure (due to loss, acquisition, variation in the position of individual sections) or their number, such diseases are classified as chromosomal. The most common chromosomal abnormalities are duodenal and allergic pathology.

Hereditary diseases can appear both immediately after the birth of a child and at different stages of life. Some of them have an unfavorable prognosis and lead to early death, while others do not significantly affect the duration or even quality of life. The most severe forms of hereditary fetal pathology cause spontaneous abortion or are accompanied by stillbirth.

Thanks to the advances in medical development, about a thousand hereditary diseases today can be detected even before the birth of a child using prenatal diagnostic methods. The latter include ultrasound and biochemical screening of the I (10-14 weeks) and II (16-20 weeks) trimesters, which are carried out to all pregnant women without exception. In addition, if there are additional indications, invasive procedures may be recommended: chorionic villus biopsy, amniocentesis, cordocentesis. If the fact of severe hereditary pathology is reliably established, the woman is offered an artificial termination of pregnancy for medical reasons.

All newborns in the first days of their life are also subject to examination for hereditary and congenital metabolic diseases (phenylketonuria, adrenogenital syndrome, congenital adrenal hyperplasia, galactosemia, cystic fibrosis). Other hereditary diseases that were not recognized before or immediately after the birth of a child can be detected using cytogenetic, molecular genetic, and biochemical research methods.

Unfortunately, a complete cure for hereditary diseases is currently not possible. Meanwhile, with some forms of genetic pathology, a significant extension of life and ensuring its acceptable quality can be achieved. In the treatment of hereditary diseases, pathogenetic and symptomatic therapy is used. The pathogenetic approach to treatment involves replacement therapy (for example, with blood coagulation factors in hemophilia), limiting the use of certain substrates for phenylketonuria, galactosemia, maple syrup disease, replenishing the deficiency of a missing enzyme or hormone, etc. Symptomatic therapy includes the use a wide range of medications, physiotherapy, rehabilitation courses (massage, exercise therapy). Many patients with genetic pathology from early childhood need correctional and developmental classes with a speech pathologist and speech therapist.

The possibilities of surgical treatment of hereditary diseases are reduced mainly to the elimination of severe malformations that interfere with the normal functioning of the body (for example, correction of congenital heart defects, cleft lip and palate, hypospadias, etc.). Gene therapy for hereditary diseases is still rather experimental in nature and is still far from widespread use in practical medicine.

The main direction of prevention of hereditary diseases is medical genetic counseling. Experienced geneticists will consult a married couple, predict the risk of having offspring with hereditary pathology, and provide professional assistance in making a decision about childbearing.

Hereditary diseases- human diseases caused by chromosomal and gene mutations. Often the terms “hereditary disease” and “congenital disease” are used as synonyms, but congenital diseases (see) are diseases present at the birth of a child; they can be caused by both hereditary and exogenous factors (for example, developmental defects associated with exposure of the embryo to radiation, chemical compounds and medications, as well as intrauterine infections).

Hereditary diseases and congenital malformations are the reason for hospitalization of children in almost 30% of cases, and taking into account diseases of unknown nature, which can largely be associated with genetic factors, this percentage is even higher. However, not all hereditary diseases are classified as congenital, since many of them appear after the neonatal period (for example, Huntington's chorea develops after 40 years). The term “family diseases” should also not be considered as a synonym for the term “hereditary diseases”, since family diseases can be caused not only by hereditary factors, but also by living conditions or professional traditions of the family.

Hereditary diseases have been known to mankind since ancient times. Klin, their study began at the end of the 18th century. In 1866, V. M. Florinsky, in the book “Improvement and Degeneration of the Human Race,” gave a correct assessment of the importance of the environment in the formation of hereditary characteristics, the harmful effects on the offspring of closely related marriages, and described the inheritance of a number of pathological characteristics (deaf muteness, retinitis pigmentosa, albinism , cleft lip, etc.). English biologist F. Galton was the first to raise the question of human heredity as a subject of scientific study. He substantiated the genealogical method (q.v.) and the twin method (q.v.) for studying the role of heredity (q.v.) and the environment in the development and formation of traits. In 1908 English. doctor Garrod (A. E. Garrod) first formulated the concept of hereditary “errors” of metabolism, thus approaching the study of the molecular basis of a number of N. b.

In the USSR a big role in development of the doctrine about N. would be. man was played by the Moscow Medical and Biological Institute. M. Gorky (later - the Medical Genetic Institute), which functioned from 1932 to 1937. This institute carried out cytogenetic studies and studied diseases with a hereditary predisposition (diabetes mellitus, peptic ulcer of the stomach and duodenum, allergies, hypertension and etc.). The Soviet neuropathologist and geneticist S. N. Davidenkov (1934) was the first to establish the existence of genetic heterogeneity of N. b. and the reasons for their wedge, polymorphism. He developed the foundations of a new type of medical care - medical genetic counseling (see Medical genetic consultation).

The discovery of the material carrier of heredity—DNA—and coding mechanisms (see Genetic code) made it possible to understand the significance of mutations in the development of N. b. L. Pauling introduced the concept of “molecular diseases”, i.e. diseases caused by a violation of the sequence of amino acids in the polypeptide chain. The introduction into the clinic of methods for separating a mixture of proteins, including enzymes, identifying the products of biochemical reactions, advances in cytogenetics, and the possibility of mapping chromosomes (see Chromosome map) made it possible to clarify the nature of a number of N. b. The total number of known N. b. by the 70s 20th century reached 2 thousand

Depending on the relationship between the roles of hereditary and exogenous factors in the etiology and pathogenesis of various diseases, N.P. Bochkov proposed that all human diseases be conditionally divided into four groups.

The first group of human diseases is N. b., in which the manifestation of pathological MUTATION (see) as an etiological factor practically does not depend on the environment, edges in this case are determined only by the severity of the symptoms of the disease. Diseases of this group include all chromosomal diseases (see) and genetic N. b. with full manifestation, for example, Down's disease, Phenylketonuria, hemophilia, glycosidosis, etc.

In the second group of diseases, hereditary changes are also an etiological factor, however, for the manifestation of mutant genes (see Gene penetrance), a corresponding environmental influence is necessary. Such diseases include gout, some forms of diabetes mellitus, and hyperlipoproteinemia (see Lipoproteins). Such diseases more often occur with constant exposure to unfavorable or harmful environmental factors (physical or mental fatigue, poor diet, etc.). These diseases can be classified as a group of diseases with a hereditary predisposition; for some of them, the environment matters more, for others it matters less.

In the third group of diseases, etiol, the factor is the environment, however, the frequency of occurrence of diseases and the severity of their course depend on the hereditary predisposition. Diseases in this group include hypertension and atherosclerosis, peptic ulcer of the stomach and duodenum, allergic diseases, many malformations, and certain forms of obesity.

The fourth group of diseases is associated exclusively with the influence of unfavorable or harmful environmental factors; heredity plays virtually no role in their occurrence. This group includes injuries, burns, acute inf. diseases. However, genetic factors can have a certain influence on the course of the pathol, the process, i.e. on the rate of recovery, the transition of acute processes to chronic, the development of decompensation of the functions of the affected organs.

Roberts et al. (1970) calculated that among the causes of child mortality, the genetic components of the disease are determined in 42% of cases, including 11% of children who die from N. b. and 31% - from acquired diseases that developed against an unfavorable hereditary background.

Known by the 70s. 20th century N. b. are divided into three main groups.

1. Monogenic diseases: a) according to the type of inheritance - autosomal dominant, autosomal recessive, sex-linked; according to phenotypic manifestation - enzymopathies (metabolic diseases), including diseases caused by impaired DNA repair, diseases caused by pathology of structural proteins, immunopathology, including disorders in the complement system, disorders of the synthesis of transport proteins, incl. including blood proteins (hemoglobinopathies, Wilson's disease, atransferrinemia), pathology of the blood coagulation system, pathology of the transfer of substances through cell membranes, disorders of the synthesis of peptide hormones.

2. Polygenic (multifactorial) diseases or diseases with a hereditary predisposition.

3. Chromosomal diseases: polyploidy, aneuploidy, structural rearrangements of chromosomes.

Monogenic diseases are inherited in full accordance with Mendel's laws (see Mendel's laws). Most of the known N. b. caused by mutation of structural genes; the possibility of an etiological role of mutations in regulatory genes in certain diseases has so far been proven only indirectly.

With an autosomal recessive type of inheritance, the mutant gene appears only in the homozygous state. Affected boys and girls are born with equal frequency. The probability of having a sick child is 25%. Parents of sick children may be phenotypically healthy, but are heterozygous carriers of the mutant gene. The autosomal recessive type of inheritance is more typical for diseases in which the function of any enzyme (or any enzymes) is impaired - the so-called. enzymopathies (see).

Recessive inheritance linked to the X chromosome means that the effect of the mutant gene is manifested only with the XY set of sex chromosomes, i.e. in boys. The probability of having a sick boy born to a mother who is a carrier of the mutant gene is 50%. The girls are practically healthy, but half of them are carriers of the mutant gene (the so-called conductors). Parents are healthy. Often the disease is detected in the sons of the proband's sisters or his maternal cousins. A sick father does not pass the disease on to his sons. This type of inheritance is characteristic of progressive muscular dystrophy of the Duchenne type (see Myopathy), hemophilia A and B (see Hemophilia), Lesch-Nyhan syndrome (see Gout), Gunther's disease (see Gargoilism), Fabry disease (see) , genetically determined deficiency of glucose-6-phosphate dehydrogenase (some forms).

Dominant inheritance linked to the X chromosome means that the effect of a dominant mutant gene is manifested in any set of sex chromosomes (XX, XY, X0, etc.). The manifestation of the disease does not depend on gender, but it is more severe in boys. Among the children of a sick man in the case of this type of inheritance, all sons are healthy, all daughters are affected. Affected women pass on the altered gene to half of their sons and daughters. This type of inheritance can be seen in phosphate diabetes.

According to phenotypic manifestation to monogenic N. b. include enzymopathies, which constitute the most extensive and best studied group of N. b. The primary enzyme defect has been deciphered in approximately 150 enzymopathies. The following causes of enzymopathies are possible: a) the enzyme is not synthesized at all; b) the sequence of amino acids in the enzyme molecule is disrupted, i.e. its primary structure is changed; c) the coenzyme of the corresponding enzyme is absent or incorrectly synthesized; d) enzyme activity is altered due to abnormalities in other enzyme systems; e) enzyme blockade is caused by genetically determined synthesis of substances that inactivate the enzyme. Enzymopathies in most cases are inherited in an autosomal recessive manner.

A gene mutation can lead to a disruption in the synthesis of proteins that perform plastic (structural) functions. Impaired synthesis of structural proteins is a likely cause of diseases such as osteodysplasia (see) and osteogenesis imperfecta (see), Ehlers-Danlos syndrome. There is evidence of a certain role of these disorders in the pathogenesis of hereditary nephritis-like diseases - Alport syndrome and familial hematuria. As a result of abnormalities in the structure of basal and cytoplasmic membrane proteins, tissue hypoplastic dysplasia develops - a histologically detectable immaturity of tissue structures. It can be assumed that tissue dysplasia can be detected not only in the kidneys, but also in any other organs. The pathology of structural proteins is characteristic of most N. b., inherited in an autosomal dominant manner.

Diseases based on insufficient mechanisms for restoring the altered DNA molecule are under study. Violation of DNA repair mechanisms has been established in xeroderma pigmentosum (see), Bloom's syndrome (see Poikiloderma) and Cockayne syndrome (see Ichthyosis), ataxia-telangiectasia (see Ataxia), Down's disease (see), Fanconi anemia (see. Hypoplastic anemia), systemic lupus erythematosus (see).

A gene mutation can lead to the development of immunodeficiency diseases (see Immunological deficiency). In the most severe forms, agammaglobulinemia occurs (see), especially in combination with aplasia of the thymus. In 1949, L. Pauling et al. found that the cause of the abnormal structure of hemoglobin in sickle cell anemia (see) is the replacement in the hemoglobin molecule of the residue glutamine to - you on the residue of valine. It was later determined that this replacement was the result of a gene mutation. This was the beginning of intensive research into hemoglobinopathies (see).

A number of mutations in the genes that control the synthesis of blood coagulation factors are known (see Blood Coagulation System). Genetically determined disorders in the synthesis of antihemophilic globulin (factor VIII) lead to the development of hemophilia A. If the synthesis of the thromboplastic component (factor IX) is impaired, hemophilia B develops. The lack of a thromboplastin precursor underlies the pathogenesis of hemophilia C.

Gene mutations can cause disruption of the transport of various compounds (organic compounds, ions) through cell membranes. The most studied hereditary pathology of amino acid transport in the intestines and kidneys, glucose and galactose malabsorption syndrome, the consequences of disruption of the potassium-sodium “pump” of the cell are being studied. An example of a disease caused by a hereditary defect in amino acid transport is Cystinuria (see), clinically manifested by nephrolitase and signs of pyelonephritis. Classic cystinuria is caused by a violation of the transport of a number of diambrocarbonic acids (arginine, lysine) and cystine through cell membranes both in the intestines and in the kidneys, and is less common than hypercystinuria, which is characterized only by a violation of the transport of cystine through cell membranes in the kidneys, while Nephrolithiasis rarely develops. This explains the apparent contradictions in the literature data on the frequency of hypercystinuria as a biochemical sign and cystinuria as a disease.

Pathology of glucose reabsorption in the renal tubules - renal glycosuria is associated with dysfunction of membrane transport proteins or with defects in the system of providing energy for the processes of active glucose transport; inherited in an autosomal dominant manner. Violation of bicarbonate reabsorption in the proximal nephron or impaired secretion of hydrogen ions by the cells of the renal epithelium of the distal nephron underlies two types of renal tubular acidosis (see Lightwood-Albright syndrome).

Cystic fibrosis can also be attributed to diseases, in the pathogenesis of which a significant role is played by a violation of the transmembrane transfer and secretory function of the exocrine glands. Known diseases, in which the function of the membrane mechanisms responsible for maintaining the normal concentration gradient of K + and Mg 2+ ions inside and outside the cell is impaired, which is clinically manifested by periodic attacks of tetany.

Polygenic (multifactorial) diseases or diseases with a hereditary predisposition are caused by the interaction of several or many genes (polygenic systems) and environmental factors. The pathogenesis of diseases with a hereditary predisposition, despite their prevalence, has not been studied enough. Deviations from the normal variants of the structure of structural, protective and enzymatic proteins can determine the existence of numerous diatheses in childhood. Of great importance is the search for phenotypic markers of hereditary predisposition to a particular disease; for example, allergic diathesis can be diagnosed based on elevated levels of immunoglobulin E in the blood and increased excretion of minor metabolites of tryptophan in the urine. Biochemical markers of hereditary predisposition to diabetes mellitus (glucose tolerance test, determination of immunoreactive insulin), constitutional-exogenous obesity, hypertension (hyperlipoproteinemia) were determined. Advances have been made in studying the relationship between AB0 blood groups (see Group-Specific Substances), the haptoglobin system, HLA antigens, and diseases. It has been established that for persons with tissue haplotype HLA-B8 there is a high risk of chronic diseases, hepatitis, celiac disease and myasthenia gravis; for persons with the HLA-A2 haplotype - chronic. glomerulonephritis, leukemia; for persons with the HLA-DW4 haplotype - rheumatoid arthritis, for persons with the HLA-A1 haplotype - atopic allergy. Connection with the HLA histocompatibility system has been found for about 90 human diseases, many of which are characterized by immune disorders.

Chromosomal diseases are divided into anomalies caused by changes in the number of chromosomes (polyploidy, aneuploidy) or structural rearrangements of chromosomes - deletions (see), inversions (see), translocations (see), duplications (see). Chromosomal mutations that have arisen in germ cells (gametes) are manifested in the so-called. full forms. Nondisjunction of chromosomes and the structural changes which developed at early stages of crushing of a zygote lead to development of mosaicism (see).

The risk of recurrence of most chromosomal diseases in the family does not exceed 1%. The exception is made by syndromes of a translocation, at to-rykh the size of repeated risk reaches 30% and more. The likelihood of chromosomal aberrations increases sharply in women over 35 years of age.

Wedge, classification N. b. is built on an organ and system principle and does not differ from the classification of acquired diseases. According to this classification, N. b. is distinguished. nervous and endocrine systems, lungs, cardiovascular system, liver, gastrointestinal tract. tract, kidneys, blood systems, skin, ear, nose, eyes, etc. This classification is conditional, since most N. b. characterized by involvement in patol, the process of several organs or systemic tissue damage.

Frequency of monogenic N. b. varies among different ethnic groups in different geographical areas. This is clearly demonstrated by the concentration of sickle cell anemia and thalassemia in geographic regions with high exposure to malaria. The prevalence of diseases with a hereditary predisposition is largely determined by balanced polymorphism (see). The concentration of a number of monogenic N. may also be associated with this phenomenon. (Phenylketonuria, cystic fibrosis, hemoglobinopathies, etc.). Features of the geographical distribution of N. b. also depend on genetic drift and the founder effect. Within just 200 years, porphyria genes spread in South Africa in this way. The concentration of mutant genes in limited areas is associated with the frequency of consanguineous marriages, especially high in isolates (see).

In Western Europe and the USSR, the most common N. b. metabolism are cystic fibrosis (see) - 1: 1200 - 1: 5000; Phenylketonuria (see) - 1: 12000 - 1: 15000; galactosemia (see) - 1: 20000 - 1: 40000; Cystinuria - 1: 14000; histidinemia (see) - 1: 17000. The frequency of hyperlipoproteinemia (including polygenically inherited forms) reaches 1: 100 - 1: 200. To frequently occurring N. b. exchange should be attributed to hypothyroidism (see) - 1: 7000; malabsorption syndrome (see) - 1: 3000; adrenogenital syndrome (see) - 1: 5000 - 1: 11000, hemophilia - 1: 10000 (boys are affected).

Diseases such as leucinosis and homocystinuria are relatively rare, their frequency is 1: 200,000 - 1: 220,000. The frequency of a significant number of N. b. exchange due to purely technical limitations (lack of express diagnostic methods, complexity of analytical studies to confirm the diagnosis) has not been established, although this does not indicate their rarity.

Diseases with a hereditary predisposition also have characteristics of distribution in different countries. Thus, according to Shands (1963), the frequency of cleft lip and palate in England is 1: 515, in Japan - 1: 333, while spina bifida in England is 10 times more common than in Japan, and congenital hip dislocation is 10 times more common in Japan than in England.

The frequency of all chromosomal diseases among newborns, according to Kaback (M. M. Kaback, 1978), is 5.6: 1000, while all types of aneuploidies, including mosaic forms, are 3.7: 1000, autosomal trisomies and structural rearrangements - 1.9: 1000. Half of all cases of structural rearrangements of chromosomes are familial cases, all trisomies are sporadic cases, that is, a consequence of newly occurring mutations. According to Polani (P. Polani, 1970), about 7% of all pregnancies are complicated by chromosomal aberrations of the fetus, which in the vast majority of cases lead to spontaneous abortions. The frequency of chromosomal aberrations in premature infants is 3-4 times higher than in full-term infants and amounts to 2-2.5%.

Diagnosis of a number of N. b. does not present significant difficulties and is based on data obtained as a result of a general clinical examination (for example, Down's disease, hemophilia, gargoilism, adrenogenital syndrome, etc.). However, in most cases, when diagnosing them, serious difficulties arise due to the fact that many N. b. according to the wedge, the manifestations are very similar to acquired diseases - the so-called. phenocopies of N. b. A number of phenotypically similar but genetically heterogeneous diseases are known to exist (eg, Marfan syndrome and homocystinuria, galactosemia and Lowe's syndrome, phosphate diabetes and renal tubular acidosis). All cases of atypically occurring or chronic diseases require clinical and genetic analysis. On N. b. may indicate the presence of specific wedge signs. Among them, signs of dysplasia may be of particular diagnostic importance - epicanthus, hypertelorism, saddle nose, structural features of the face (“bird-like”, “doll-like”, oligomimic face, etc.), skull (dolichocephaly, brachycephaly, plagiocephaly, “buttock” shape of the skull and etc.), eyes, teeth, limbs, etc.

If you suspect N. b. A genetic examination of a patient begins with obtaining detailed clinical and genealogical data based on a survey about the health status of immediate and distant relatives, as well as a special examination of family members, which makes it possible to compile a medical report. the patient’s pedigree and determine the nature of inheritance of the pathology (see Genealogical method). Various paraclinical methods are of auxiliary (and in some cases decisive) diagnostic importance, including biochemical and cytochemical studies, electron microscopy of cells, etc. Biochemical and methods for diagnosing metabolic disorders based on the use of chromatography have been developed (see .), electrophoresis (see), ultracentrifugation (see), etc. To diagnose diseases caused by enzyme deficiency, methods are used to determine the activity of these enzymes in plasma and blood cells, in material obtained from organ biopsies, in tissue culture .

Carrying out biochemical studies for N. b. metabolism in some cases requires the use of loading tests with compounds whose metabolism is believed to be impaired. The expansion of diagnostic capabilities is associated with the development and practical use of methods for isolation, purification and determination of physical and chemical. characteristics, including kinetic, of enzymes of blood cells and tissue cultures in N. b.

However, complex analytical methods cannot be used for mass surveys. In this regard, a two-stage examination is carried out using simple semi-quantitative methods at the initial stage and, if the results of the first stage are positive, analytical methods; these programs are called sifting or screening (see).

For semi-quantitative determination of the content of amino acids, galactose and a number of other compounds in the blood, microbiological methods are most often used (see Guthrie method). In a number of laboratories, thin layer chromatography is used at the nerve stage. In some cases, radiochemical methods are used, for example, to detect hypothyroidism in newborns. The introduction of methods of automatic biochemical analysis facilitates mass examination of children for N. b.

In many countries, mass screening is carried out, in which all newborns or older children are examined, and the so-called. selective screening, when only children from specialized institutions (somatic, psychoneurological, ophthalmological and other hospitals) are examined.

Mass examinations of children (especially newborns) make it possible to identify hereditary metabolic disorders in the preclinical stage, when diet therapy and appropriate medications can completely prevent the development of severe disability.

The development of new methods of cell cultivation, biochemical, and cytogenetic studies have made it possible to prenatally diagnose N., including all chromosomal diseases and diseases linked to the X chromosome, as well as a number of hereditary metabolic disorders. The results of the study may serve as an indication for termination of pregnancy or the beginning of treatment for metabolic abnormalities in the prenatal period. Prenatal diagnosis N. b. is indicated in cases where one of the parents has a structural rearrangement of chromosomes (translocations, inversions), when the age of pregnant women exceeds 35 years and when dominantly inherited diseases are traced in the family or there is a high risk of recessive hereditary diseases - autosomal or X-linked chromosome.

Vitamins can also induce the synthesis of enzymes, and this is especially noticeable in the so-called. vitamin-dependent conditions, which are characterized by the development of hypo- or avitaminosis not due to a limited supply of vitamins to the body, but as a result of impaired synthesis of specific transport proteins or apoenzymes (see Enzymes). The effectiveness of high doses of vitamin B 6 (from 100 mg and above per day) is well known for the so-called. pyridoxine-dependent conditions and diseases (cystathioninuria, homocystinuria, familial hypochromic anemia, as well as Knapp-Comrover syndrome, Hartnup disease, certain forms of bronchial asthma). High doses of vitamin D (up to 50,000-200,000 IU per day) have been effective in hereditary rickets-like diseases (phosphate diabetes, de Toni-Debreu-Fanconi syndrome, renal tubular acidosis). Vitamin C in doses of up to 1000 mg per day is used in the treatment of alkaptonuria. High doses of vitamin A are prescribed to patients with Hurler and Gunther syndromes (mucopolysaccharidosis). There was an improvement in the condition of patients with mucopolysaccharidosis under the influence of prednisolone.

In the treatment of Hereditary diseases, the principle of suppressing metabolic reactions is used, but for this it is necessary to have a clear understanding of the influence of chemical precursors or metabolites of the blocked reaction on the functions of certain systems.

Advances in plastic and reconstructive surgery have determined the high efficiency of surgical treatment of hereditary and congenital malformations. It is promising to introduce into the practice of treating N. b. transplantation methods, which will allow not only to replace organs that have undergone irreversible changes, but also to carry out transplants in order to restore the synthesis of proteins and enzymes that are absent in patients. Transplantation of immunocompetent organs (thymus gland, bone marrow) in the treatment of various forms of hereditary immune deficiency can be of great scientific and practical interest.

One of the methods of treating N. b. is the prescription of drugs that bind toxic products formed as a result of blocking certain biochemical reactions. Thus, for the treatment of hepatocerebral dystrophy (Wilson-Konovalov disease), drugs that form soluble complex compounds with copper (unithiol, penicillamine) are used. Complexons (see), which specifically bind iron, are used in the treatment of hemochromatosis, and complexons, which form soluble complex calcium compounds, are used in the treatment of hereditary tubulopathies with nephrolithiasis. In the treatment of hyperlipoproteinemia, cholestyramine is used, which binds cholesterol in the intestine and prevents its reabsorption.

The search for means of influence that can be used by genetic engineering is in the development stage (see).

Advances in the prevention and treatment of N. b. will primarily be associated with the creation of a system of dispensary services for patients with hereditary diseases. Based on the order of the USSR Minister of Health No. 120 of October 31, 1979, “On the status and measures to further improve the prevention, diagnosis and treatment of hereditary diseases,” 80 medical consultation rooms will be organized in the USSR. genetics, and also created centers for medical genetic counseling, hereditary pathology in children and prenatal hereditary pathology.

Preserving and improving the health of the population depends to a large extent on the prevention of N.B., this is where the particularly important role of genetics lies, studying the intimate mechanisms of all body functions and their disorders.

Certain hereditary diseases - see articles on the names of diseases.

Modeling of hereditary diseases

Modeling of hereditary diseases consists of reproducing hereditary human diseases (one pathol, process or fragment of a pathological process) on animals or their organs, tissues and cells in order to establish the etiology and pathogenesis of these diseases and develop methods for their treatment.

Modeling has played a major role in the development of effective methods for treating and preventing infections. diseases. In the early 60s. 20th century Laboratory animals (mice, rats, rabbits, hamsters, etc.) began to be widely used as model objects for studying human hereditary pathology. Models of N. b. Humans can also include farm and wild animals, both vertebrates and invertebrates.

Possibility of N.'s modeling. is primarily associated with the presence in humans and animals of homologous loci that control similar metabolic processes in normal and pathological conditions. Moreover, according to the law of homological series in hereditary variability, formulated by N.I. Vavilov in 1922, the closer the species are located to each other in their evolutionary relationship, the more homologous genes they should have. In mammals, metabolic processes, as well as the structure and functions of organs, are similar, so such animals are of the greatest interest for the study of N. b. person.

From the point of view of etiology, animal modeling of those hereditary human anomalies that are caused by gene mutations is more justified. This is explained by the greater likelihood that humans and animals have homologous genes than homologous regions (segments) or entire chromosomes. Lines of animals that are carriers of the same hereditary anomaly resulting from a gene mutation are called mutant.

A prerequisite for successful modeling of N. b. human on animals is the homology or identity of diseases in humans and mutant animals, as evidenced by the unambiguity or similarity of gene effects. Modeling of N. b. human can also be carried out on isolated organs, tissues or cells. Partial modeling is of great scientific and practical interest, i.e., reproducing not the entire disease as a whole, but only one pathol, process or even a fragment of such a process.

As a result of the complex interaction of the products of many genes and the existence of homeostatic mechanisms in higher vertebrates, the final effects of different mutant genes may be largely similar. However, this does not yet indicate the uniformity of the action of the genes causing the anomalies and the similarity of pathogenesis. Consequently, there are more specific differences in the primary than in the secondary or final effects of mutant genes. Therefore, in most cases one should expect more pronounced features in the action of genes at the molecular or cellular level than at the level of the whole organism. This explains the desire of experimenters to detect a primary genetically determined deviation from the norm in order to correctly understand the pathogenesis of the anomaly and clearly distinguish between clinically similar forms of diseases.

The possibility of using a large number of animals at various stages of pathol development is of great importance for clarifying and specifying the pathogenesis of anomalies and developing methods for their therapy and prevention.

There are many mutant animal lines known that are of interest as models of N. b. person. Intensive research is being carried out on some of them, in particular on mouse lines with hereditary obesity, immunodeficiency conditions, diabetes, muscular dystrophy, retinal degeneration, etc. Great importance is attached to active searches for anomalies in animals that are similar to certain Hereditary human diseases. Animals in which such anomalies are found should be preserved, since they are of great interest for medicine.

Bibliography: Antenatal diagnosis of genetic diseases, ed. A. E. X. Emery, trans. from English, M., 1977; Badalyan L. O., Tabolin V. A. and Veltishchev Yu. E. Hereditary diseases in children, M., 1971; Barashnev Yu. I. and Veltishchev Yu. E. Hereditary metabolic diseases in children, M., 1978, bibliogr.; Bochkov N.P. Human Genetics, M., 1978, bibliogr.; Davidenkova E. F. and Liberman I. S. Clinical genetics, L., 1975, bibliogr.; Grooms BV Biological modeling of hereditary diseases, M., 1969, bibliogr.; Neifakh SA Biochemical mutations in humans and experimental approaches to their specific treatment, Zhurn. All-Union. chem. about-va them. D. I. Mendeleev, vol. 18, No. 2, p. 125, 1973, bibliogr.; Harris G. Fundamentals of human biochemical genetics, trans. from English, M., 1973, bibliogr.; Efroimson V.P. Introduction to medical genetics, M., 1968; Cabask M. M. Medical genetics an overview, Pediat. Clin. N. Amer., v. 24, p. 395, 1978; Knapp A. Genetisclie Stoffwechselstorungen, Jena, 1977, Bibliogr.; Lenz W. Medizinische Genetik, Stuttgart, 1976, Bibliogr.; McKusick Y. Mendelian inheritance in man, Baltimore, 1978; Medical genetics, ed. by G. Szab6 a. Z. Papp, Amsterdam, 1977; The metabolic basis of inherited diseases, ed. by J. B. Stanbury a. o., N.Y., 1972.

Yu. E. Veltishchev; B.V. Konyukhov (gen.).

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Hereditary diseases are diseases the appearance and development of which are associated with complex disorders in the hereditary apparatus of cells transmitted through gametes (reproductive cells). The occurrence of such ailments is caused by disturbances in the processes of storage, implementation and transmission of genetic information.

Causes of hereditary diseases

The basis of diseases of this group are mutations of gene information. They can be detected in a child immediately after birth, or they can appear in an adult after a long time.

The appearance of hereditary diseases can be associated with only three reasons:

1. Chromosome disruption. This is the addition of an extra chromosome or the loss of one of the 46.
2. Changes in chromosome structure. Diseases are caused by changes occurring in the reproductive cells of the parents.
3. Gene mutations. Diseases arise due to mutations of both individual genes and due to disruption of a complex of genes.

Gene mutations are classified as hereditarily predisposed, but their manifestation depends on the influence of the external environment. That is why the causes of such hereditary diseases as diabetes mellitus or hypertension, in addition to mutations, also include poor nutrition, prolonged overstrain of the nervous system, and mental trauma.

Types of hereditary diseases

The classification of such diseases is closely related to the causes of their occurrence. Types of hereditary diseases are:

• genetic diseases - arise as a result of DNA damage at the gene level;
• chromosomal diseases - associated with a complex abnormality in the number of chromosomes or with their aberrations;
• diseases with hereditary predisposition.

For quality treatment, knowing what hereditary human diseases there are is not enough; it is imperative to identify them in time or the likelihood of their occurrence. To do this, scientists use several methods:

1. Genealogical. By studying a person's pedigree, it is possible to identify the inheritance characteristics of both normal and pathological characteristics of the body.
2. Twin. This diagnosis of hereditary diseases is a study of the similarities and differences of twins to identify the influence of the external environment and heredity on the development of various genetic diseases.
3. Cytogenetic. The study of the structure of chromosomes in sick and healthy people.
4. Biochemical method. Observing Features.

In addition, almost all women undergo ultrasound examinations during pregnancy. It makes it possible to identify congenital malformations based on fetal characteristics, starting from the first trimester, and also to suspect the presence of certain hereditary diseases of the nervous system or chromosomal diseases in the child.

Prevention of hereditary diseases

Until recently, even scientists did not know what the possibilities were for treating hereditary diseases. But the study of pathogenesis made it possible to find a way to cure certain types of diseases. For example, heart defects today can be successfully treated surgically.

Many genetic diseases, unfortunately, have not been fully studied. Therefore, in modern medicine, great importance is given to the prevention of hereditary diseases.

Methods for preventing the occurrence of such diseases include planning for childbearing and refusal to bear a child in cases of high risk of congenital pathology, termination of pregnancy with a high probability of fetal disease, as well as correction of the manifestation of pathological genotypes.