Hereditary human diseases. Hereditary human diseases Inheritance of human diseases

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.

From total number 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 human body various constitutional changes.

As a result of development modern science Scientists have not only counted the chromosomes, but can now identify each pair. Carrying out karyotype analyzes allows us to identify the existence of a hereditary disease on early stages human 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, negative conditions ecology.
• 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 disorder.
• diseases directly related to inherited predisposition. In the presence of serious factors associated with external conditions, it may develop bronchial asthma, atherosclerosis, some heart diseases, ulcers, etc. Harmful factors You can name poor quality nutrition, negative ecology, thoughtless taking of medications, 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 male body this chromosome is unpaired, thereby preserving the manifestation of a hereditary disease in men. IN female body there is a pair of “X”, so women are considered carriers of a low-quality X chromosome. In order to chromosomal hereditary diseases were transmitted exclusively by 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 numbers about 5500-6500 clinical forms gene diseases. These data are indicative due to the lack of clear boundaries when dividing separate forms. Some genetic hereditary diseases represent various shapes from a clinical point of view, but from a genetic point of view, they are the consequences of a mutation in one locus.

Scientists claim that appearance person, health status and others individual characteristics depend on two main factors: genetics and influence environment. 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 inability complete cure. Pneumonia and sore throat can be treated with antibiotics, an inflamed appendix or gallbladder- delete. 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 one possible way Treatment of hereditary diseases is therapy aimed at eliminating symptoms and improving 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. main reason Myopia is a family history.
The cause of the disease is a feature of the muscles that promote stretching 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 the 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 - pathological condition, which increases blood clotting. 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, nevertheless, it is thrombophilia that often leads to ischemic heart attacks, strokes, thromboembolism pulmonary artery, 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 this state the children of the sick will inherit.

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 respiratory and digestive system. 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 immobilization 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 DPT vaccinations, which is fundamentally wrong, 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.

Today, more than four and a half thousand hereditary diseases are known, and each case has a solid evidence base that the disease is transmitted precisely by inheritance, and nothing else. But despite high level development of diagnostics, not all genetic pathologies have been studied to the extent of biochemical reactions. However, the basic mechanisms for the development of hereditary diseases are known to modern science.

There are three basic types of mutations:

• Genetic;
• Chromosomal;
• Genomic (mostly sex-linked).

Mendel's fundamental genetic laws define dominant and recessive genes. After fertilization, the fetal cells contain half the genes of the mother and half of the father, making up pairs - alleles. There are not many genetic combinations: only two. Defining characteristics are manifested in the phenotype. If one of the mutated genes of the allele is dominant, the disease manifests itself. The same thing happens with a dominant couple. If such a gene is recessive, this is not reflected in the phenotype in any way. The manifestation of hereditary diseases transmitted by a recessive trait is only possible if both genes carry pathological information.

Chromosomal mutations are manifested by a violation of their division during the process of meiosis. As a result of duplication, additional chromosomes appear: both sex and somatic.

Sex-linked hereditary anomalies are transmitted via the sex X chromosome. Since in men it is represented in singular, all males in the family have manifestations of the disease. Whereas women who have two sex X chromosomes are carriers of a damaged X chromosome. For a sex-linked hereditary disease to occur in women, it is necessary that the patient inherits both defective sex chromosomes. This happens quite rarely.

Biology of hereditary diseases

Manifestations of hereditary pathology depend on many factors. The characters inherent in the genotype have external manifestations(affect the phenotype) under certain conditions. In this regard, the biology of hereditary diseases divides all genetically determined diseases into the following groups:

• Manifestations independent of external environment, education, social conditions, welfare: phenylketonuria, Down's disease, hemophilia, sex chromosome mutations;
• A hereditary predisposition that manifests itself only under certain conditions. Great importance have environmental factors: diet, occupational hazards, etc. Such diseases include: gout, atherosclerosis, peptic ulcer, arterial hypertension, diabetes mellitus, alcoholism, tumor cell growth.

Sometimes, signs of even non-inherited diseases are found in children of sick people. This is facilitated by the same susceptibility of relatives to certain factors. For example, the development of rheumatism, the causative agent of which has nothing to do with genes and chromosomes. However, children, grandchildren and great-grandchildren are also susceptible systemic damage connective tissueβ-hemolytic streptococcus. Many people chronic tonsillitis accompanies all life, but does not cause hereditary diseases, while those who have relatives with rheumatic lesions of the heart valves develop a similar pathology.

Causes of hereditary diseases

Causes of hereditary diseases associated with gene mutations, are always the same: gene defect – enzyme defect – lack of protein synthesis. As a result, substances accumulate in the body that should have been converted into necessary elements, but in themselves, as intermediate products of biochemical reactions, are toxic.

For example, the classic hereditary disease phenylketonuria is caused by a defect in the gene that regulates the synthesis of the enzyme that converts phenylalanine into tyrosine. Therefore, with phenylketonuria, the brain suffers.

Lactase deficiency causes intestinal upset. Intolerance to raw cow's milk is a fairly common phenomenon, and it also applies to hereditary diseases, although, under certain conditions, compensation may occur in some people, and lactase production is improved due to the active “training” of intestinal cells.

Chromosomal abnormalities appear regardless of conditions. Many children are simply not viable. But Down's disease is one of those hereditary diseases in which external conditions environments may be so favorable that patients become full members of society.

Defects in the division of sex chromosomes are not accompanied by fatal complications, since they do not affect somatic symptoms. All vital organs are not affected by such hereditary diseases. Damage is found at the level of the genital organs, often only internal ones. Sometimes it works without them. For example, in triplo-ex syndrome, when a woman has an extra X chromosome, her ability to conceive is preserved. And children are born with a normal set of sex chromosomes. The situation is similar with the additional Y chromosome in men.

The mechanism for the development of hereditary diseases lies in a combination of genes: dominant and recessive. Their different combinations manifest themselves differently in the phenotype. For the development of the disease, one mutated dominant gene or a pathological recessive pair in one allele is sufficient.

Prevention of hereditary diseases

Preventing manifestations genetic pathology are carried out by specialists from genetic centers. IN antenatal clinics major cities There are special offices of geneticists who provide counseling to future married couples. Prevention of hereditary diseases is carried out by drawing up genealogical maps and deciphering special tests.

From parents, a child can acquire not only a certain eye color, height or face shape, but also inherited ones. What are they? How can you detect them? What classification exists?

Mechanisms of heredity

Before talking about diseases, it is worth understanding what they are. All information about us is contained in the DNA molecule, which consists of an unimaginably long chain of amino acids. The alternation of these amino acids is unique.

The fragments of a chain of DNA are called genes. Each gene contains complete information about one or more characteristics of the body, which is transmitted from parents to children, for example, skin color, hair, character trait, etc. When they are damaged or their work is disrupted, problems arise. genetic diseases, transmitted by inheritance.

DNA is organized into 46 chromosomes or 23 pairs, one of which is the sex chromosome. Chromosomes are responsible for gene activity, copying, and recovery from damage. As a result of fertilization, each couple has one chromosome from the father and another from the mother.

In this case, one of the genes will be dominant, and the other will be recessive or suppressed. To put it simply, if the father’s gene responsible for eye color turns out to be dominant, then the child will inherit this trait from him, and not from the mother.

Genetic diseases

Inherited diseases occur when disturbances or mutations occur in the mechanism for storing and transmitting genetic information. An organism whose gene is damaged will pass it on to its descendants in the same way as healthy material.

In the case when the pathological gene is recessive, it may not appear in the next generations, but they will be its carriers. The chance that it will not manifest itself exists when a healthy gene also turns out to be dominant.

Currently, more than 6 thousand hereditary diseases are known. Many of them appear after 35 years, and some may never make themselves known to the owner. Diabetes mellitus, obesity, psoriasis, Alzheimer's disease, schizophrenia and other disorders occur with extremely high frequency.

Classification

Genetic diseases that are inherited have great amount varieties. To divide them into separate groups, the location of the violation, causes, clinical picture, nature of heredity.

Diseases can be classified according to the type of inheritance and location of the defective gene. So, it is important whether the gene is located on the sex or non-sex chromosome (autosome), and whether it is suppressive or not. Diseases are distinguished:

• Autosomal dominant - brachydactyly, arachnodactyly, ectopia lentis.
• Autosomal recessive - albinism, muscular dystonia, dystrophy.
• Limited by gender (observed only in women or men) - hemophilia A and B, color blindness, paralysis, phosphate diabetes.

The quantitative and qualitative classification of hereditary diseases distinguishes genetic, chromosomal and mitochondrial types. The latter refers to DNA disorders in mitochondria outside the nucleus. The first two occur in DNA, which is found in the cell nucleus, and have several subtypes:

Monogenic	Mutations or absence of a gene in nuclear DNA.	Marfan syndrome, adrenogenital syndrome in newborns, neurofibromatosis, hemophilia A, Duchenne myopathy.
Polygenic	Predisposition and action	Psoriasis, schizophrenia, ischemic disease, cirrhosis, bronchial asthma, diabetes mellitus.
Chromosomal
	Changes in chromosome structure.	Miller-Dicker, Williams, Langer-Gidion syndromes.
	Change in the number of chromosomes.	Down's, Patau's, Edwards', Klifenter's syndromes.

Causes

Our genes tend not only to accumulate information, but also to change it, acquiring new qualities. This is a mutation. It occurs quite rarely, approximately 1 time in a million cases, and is transmitted to descendants if it occurs in germ cells. For individual genes, the mutation frequency is 1:108.

Mutations are natural process and form the basis of the evolutionary variability of all living beings. They can be useful and harmful. Some help us better adapt to the environment and way of life (for example, the opposite thumb hands), others lead to diseases.

The occurrence of pathologies in genes is increased by physical, chemical and biological factors. Some alkaloids, nitrates, nitrites, some food additives, pesticides, solvents and petroleum products have this property.

Among physical factors there are ionizing and radioactive radiation, ultraviolet rays, excessively high and low temperatures. As biological reasons rubella viruses, measles, antigens, etc. appear.

Genetic predisposition

Parents influence us not only through upbringing. It is known that some people are more likely to develop certain diseases than others due to heredity. Genetic predisposition to diseases occurs when one of the relatives has abnormalities in genes.

The risk of a particular disease in a child depends on his gender, because some diseases are transmitted only through one line. It also depends on the person's race and the degree of relationship with the patient.

If a person with the mutation gives birth to a child, the chance of inheriting the disease will be 50%. The gene may well not manifest itself in any way, being recessive, and in the case of marriage with healthy person, its chances of being passed on to descendants will be 25%. However, if the spouse also has such a recessive gene, the chances of its manifestation in the descendants will again increase to 50%.

How to identify the disease?

The genetic center will help to detect the disease or predisposition to it in time. Usually everyone has one major cities. Before taking the tests, a consultation is held with a doctor to find out what health problems are observed in relatives.

A medical genetic examination is carried out by taking blood for analysis. The sample is carefully examined in the laboratory for any abnormalities. Expectant parents usually attend such consultations after pregnancy. However, it is worth coming to the genetic center during its planning.

Hereditary diseases seriously affect the mental and physical health child, affect life expectancy. Most of them are difficult to treat, and their manifestation can only be corrected medical supplies. Therefore, it is better to prepare for this even before conceiving a baby.

Down syndrome

One of the most common genetic diseases is Down syndrome. It occurs in 13 cases out of 10,000. This is an anomaly in which a person has not 46, but 47 chromosomes. The syndrome can be diagnosed immediately at birth.

The main symptoms include a flattened face, raised corners of the eyes, short neck and lack muscle tone. Ears, as a rule, small, the eye shape is oblique, the shape of the skull is irregular.

Sick children have comorbid disorders and diseases - pneumonia, ARVI, etc. Exacerbations may occur, for example, loss of hearing, vision, hypothyroidism, heart disease. With downism it is slowed down and often remains at the level of seven years.

Constant work, special exercises and medications significantly improve the situation. There are many cases where people with a similar syndrome were quite able to lead an independent life, find work and achieve professional success.

Hemophilia

A rare hereditary disease that affects men. Occurs once in 10,000 cases. Hemophilia has no cure and occurs as a result of a change in one gene on the sex X chromosome. Women are only carriers of the disease.

The main characteristic is the absence of a protein that is responsible for blood clotting. In this case, even a minor injury causes bleeding that is not easy to stop. Sometimes it manifests itself only the next day after the injury.

Queen Victoria of England was a carrier of hemophilia. She passed the disease on to many of her descendants, including Tsarevich Alexei, the son of Tsar Nicholas II. Thanks to her, the disease began to be called “royal” or “Victorian”.

Angelman syndrome

The disease is often called “happy doll syndrome” or “Parsley syndrome”, as patients experience frequent outbursts of laughter and smiling, and chaotic hand movements. This anomaly is characterized by disturbances in sleep and mental development.

The syndrome occurs once in 10,000 cases due to the absence of certain genes on the long arm of chromosome 15. Angelman disease develops only if genes are missing from the chromosome inherited from the mother. When the same genes are missing from the paternal chromosome, Prader-Willi syndrome occurs.

The disease cannot be completely cured, but it is possible to alleviate the symptoms. For this purpose, physical procedures and massages are performed. Patients do not become completely independent, but during treatment they can take care of themselves.

By determining the formation of a person’s phenotype during its development, heredity and environment play a certain role in the development of a defect or disease. However, the share of participation of genetic and environmental factors varies with different states. From this point of view, the forms of deviations from normal development It is customary to divide into 3 groups: hereditary diseases (chromosomal and genetic), multifactorial diseases.

Hereditary diseases. Depending on the degree of damage to the genetic material, chromosomal and gene diseases. The development of these diseases is entirely due to defects in the hereditary program, and the role of the environment is to modify the phenotypic manifestations of the disease. This group includes chromosomal and genomic mutations and multigene inherited diseases. Hereditary diseases are always associated with a mutation, however, the phenotypic manifestations of the latter and the degree of severity may vary in different individuals. In some cases this is due to the dose of the mutant allele, in others – due to environmental influences.

Multifactorial diseases (diseases with hereditary predisposition). These are mainly diseases of mature and old age. The reasons for their development are environmental factors, but the degree of their implementation depends on the genetic constitution of the organism.

Human chromosomal diseases

This group of diseases is caused by changes in the structure of individual chromosomes or a certain number of them in the karyotype (imbalance of hereditary material). In humans, genomic mutations of the polyploidy type have been described, which occur in aborted embryos (fetuses) and stillborns. The main part of chromosomal diseases are aneuploidies. Most of them concern chromosomes 21 and 22 and are most often found in mosaics (individuals having cells with a mutant and normal karyotype). Trisomies are described for a large number of autosomes and the X chromosome (may be present in 4-5 copies). Structural rearrangements of chromosomes are also usually an imbalance of genetic material. The degree of reduction in viability depends on the amount of missing or excess hereditary material and the type of altered chromosome.

Chromosomal changes leading to developmental defects are most often introduced into the zygote with the gamete of one of the parents. In this case, all the cells of the new organism will have an abnormal chromosome set (for diagnosis, it is enough to analyze the karyotype of the cells of any tissue). If chromosomal abnormalities occur in one of the blastomeres during the first divisions of a zygote formed from normal gametes, then a mosaic organism develops. To determine the probability of occurrence chromosomal disease in the offspring of families that already have sick children, it is necessary to establish whether this disorder is new or inherited. Often, parents of sick children have a normal karyotype, and the disease is the result of mutations in one of the gametes. In this case, the likelihood of a chromosomal disorder is unlikely. In another case, in somatic cells parents have chromosomal or genomic mutations that can be transmitted to their germ cells. Chromosomal abnormalities are transmitted to the offspring by phenotypically normal parents who are carriers of balanced chromosomal rearrangements. The phenotypic manifestation of various chromosomal and genomic mutations is characterized by early and multiple lesions various systems and organs. Chromosomal diseases are characterized by a combination of many birth defects. They are also characterized by diversity and variability of phenotypic manifestations. The most specific manifestations of chromosomal diseases are associated with an imbalance in a relatively small fragment of the chromosome. An imbalance in a significant amount of chromosomal material makes the picture less specific.

The specificity of the manifestation of a chromosomal disease is determined by changes in the content of certain structural genes encoding the synthesis of specific proteins. Semi-specific manifestations of chromosomal disease are largely associated with an imbalance of genes represented by many copies that control key processes in cell life. Nonspecific manifestations with chromosomal diseases associated with changes in the content of heterochromatin in cells, which affects the normal course cell division, growth, formation of quantitative characteristics.

Human gene diseases

Among gene diseases, a distinction is made between multigene diseases, inherited in accordance with Mendel's laws, and polygenic diseases (diseases with a hereditary predisposition). Depending on the functional significance of the primary products of the corresponding genes, gene diseases are divided into:

1. violation of enzyme systems (enzymopathies);
2. defects in blood proteins (hemoglobinopathies);
3. defects in structural proteins (collagen diseases);
4. diseases with an unknown biochemical defect.

Enzymopathies

Enzymopathies are based on either a change in enzyme activity or a decrease in the intensity of its synthesis. Hereditary enzyme defects are clinically manifested in homozygous individuals, and in heterozygous individuals, insufficient enzyme activity is revealed by special studies.

Depending on the metabolic disorder, there are:

1. hereditary defects in carbohydrate metabolism (galactosemia - a disorder of the metabolism of milk sugar; mucopolysaccharidosis - a disorder of the breakdown of polysaccharides);
2. hereditary defects in lipid and lipoprotein metabolism;
3. hereditary defects in amino acid metabolism (albinism - a disorder of the synthesis of melanin pigment; tyrosinosis - a disorder of tyrosine metabolism);
4. hereditary defects in vitamin metabolism;
5. hereditary defects in the metabolism of purine pyrimidine nitrogenous bases;
6. hereditary defects in hormone biosynthesis;
7. hereditary defects of red blood cell enzymes.

Hemoglobinopathies

This group of diseases is caused by a primary defect in the peptide chains of hemoglobin and associated disruption of its properties and functions (erythrocytosis, methemoglobinemia).

Collagen human diseases

The occurrence of these diseases is based on genetic defects in the biosynthesis and breakdown of collagen, the most important component of connective tissue.

Hereditary human diseases with an unknown biochemical defect

The overwhelming number of monogenic hereditary diseases belongs to this group. The most common are:

1. cystic fibrosis - hereditary damage to the exocrine glands and glandular cells of the body;
2. achondroplasia - in most cases caused by a newly occurring mutation. This is a disease of the inert system, in which abnormalities in the development of cartilage tissue are observed.
3. muscular dystrophies (myopathies) are diseases associated with damage to striated and smooth muscles.

Human diseases with a hereditary predisposition

This group of diseases differs from genetic diseases in that they require the action of environmental factors to manifest themselves. Among them there are also monogenic and polygenic. Such diseases are called multifactorial.

Monogenic diseases with a hereditary predisposition are relatively few in number. The method of Mendeleevian genetic analysis is applicable to them. Considering important role environment in their manifestation, they are considered hereditarily determined pathological reactions to the action of various external factors (medicines, food additives, physical and biological agents), which are based on hereditary deficiency of certain enzymes. Installation using various methods genetic research accurate diagnosis, clarification of the role of environment and heredity in the development of the disease, and determination of the type of inheritance enable the doctor to develop methods for treating and preventing the occurrence of these diseases in subsequent generations.