All married couples, dreaming of a child, want the baby to be born healthy. But there is a possibility that, despite all the efforts made, the child will be born seriously ill. This often happens due to genetic diseases that occurred in the family of one of the parents or even both. What genetic diseases are the most common?

The likelihood of a genetic disease in a child

It is believed that the probability of having a baby with a congenital or hereditary pathology, the so-called population or general statistical risk, is approximately 3-5% for each pregnant woman. In emergency cases, the likelihood of having a child with a genetic disease can be predicted and the pathology can be diagnosed already during the child’s intrauterine development. Certain congenital defects and diseases are identified using laboratory-biochemical, cytogenetic and molecular-genetic techniques in the fetus, since some diseases are detected during a set of prenatal (antenatal) diagnostic methods.

Down syndrome

The most common disease caused by a change in the set of chromosomes is Down's disease, which occurs in one child in 700 newborns. This diagnosis in a child must be made by a neonatologist in the first 5-7 days after birth and confirmed by examining the child’s karyotype. If a child has Down syndrome, the karyotype is 47 chromosomes, when with 21 pairs there is a third chromosome. Girls and boys are susceptible to Down syndrome at the same rate.

Shereshevsky-Turner disease occurs only in girls. Signs of this pathology can become noticeable at the age of 10-12, when the girl’s height is too short, and the hair on the back of the head is set too low. At 13-14 years old, a girl suffering from this disease does not even have any hint of menstruation. Mild mental retardation is also noted. The main symptom in adult girls with Shereshevsky-Turner disease is infertility. The karyotype of such a patient is 45 chromosomes, one X chromosome is missing.

Kleinfelter's disease

Kleinfelter's disease occurs only in men; the diagnosis of this disease is most often made at 16-18 years of age. The sick young man has a very tall height - from 190 cm and above, with mental retardation often observed, and disproportionately long arms that can cover the entire chest. When examining the karyotype, 47 chromosomes are found - 47, XXY. In adult men with Klinefelter's disease, the main symptom is infertility.

With phenylketonuria, or pyruvic oligophrenia, which is a hereditary disease, the parents of a sick child can be completely healthy people, but each of them can be a carrier of exactly the same pathological gene, and the risk that they will have a sick child is approximately 25%. Most often, such cases occur in related marriages. Phenylketonuria is one of the common hereditary diseases, and its incidence is 1:10,000 newborns. The essence of phenylketonuria is that the amino acid phenylalanine is not absorbed by the body, and the toxic concentration negatively affects the functional activity of the brain and a number of other organs and systems of the child. There is a lag in the baby's mental and motor development, epileptiform-like seizures, dyspeptic symptoms and dermatitis - these are the main clinical signs of this disease. Treatment consists of a special diet, as well as the additional use of amino acid mixtures devoid of the amino acid phenylalanine.

Hemophilia

Hemophilia most often appears only after the child is one year old. Mostly boys suffer from this disease, but mothers are most often carriers of this genetic mutation. The bleeding disorder observed in hemophilia often leads to severe joint damage, such as hemorrhagic arthritis and other damage to the body, when even the slightest cuts cause prolonged bleeding, which can be fatal to a person.

Every gene in the human body carries unique information contained in DNA. The genotype of a particular individual provides both its unique external characteristics and largely determines its state of health.

Medical interest in genetics has been growing steadily since the second half of the 20th century. The development of this field of science opens up new methods for studying diseases, including rare ones that were considered incurable. To date, several thousand diseases have been discovered that completely depend on a person’s genotype. Let's consider the causes of these diseases, their specificity, what methods of diagnosis and treatment are used by modern medicine.

Types of genetic diseases

Genetic diseases are considered to be inherited diseases that are caused by mutations in genes. It is important to understand that congenital defects that appear as a result of intrauterine infections, the pregnant woman taking illegal drugs and other external factors that could affect pregnancy are not related to genetic diseases.

Human genetic diseases are divided into the following types:

Chromosomal aberrations (rearrangements)

This group includes pathologies associated with changes in the structural composition of chromosomes. These changes are caused by chromosome breakage, which leads to redistribution, doubling or loss of genetic material in them. It is this material that must ensure the storage, reproduction and transmission of hereditary information.

Chromosomal rearrangements lead to a genetic imbalance, which negatively affects the normal course of development of the body. Aberrations appear in chromosomal diseases: cry-the-cat syndrome, Down syndrome, Edwards syndrome, polysomies on the X chromosome or Y chromosome, etc.

The most common chromosomal abnormality in the world is Down syndrome. This pathology is caused by the presence of one extra chromosome in the human genotype, that is, the patient has 47 chromosomes instead of 46. People with Down syndrome have the 21st pair (there are 23 in total) of chromosomes in three copies, rather than the required two. There are rare cases when this genetic disease is the result of a translocation of chromosome 21 or mosaicism. In the vast majority of cases, the syndrome is not a hereditary disorder (91 out of 100).

Monogenic diseases

This group is quite heterogeneous in terms of clinical manifestations of diseases, but each genetic disease here is caused by DNA damage at the gene level. To date, over 4,000 monogenic diseases have been discovered and described. These include diseases with mental retardation, hereditary metabolic diseases, isolated forms of microcephaly, hydrocephalus and a number of other diseases. Some of the diseases are already noticeable in newborns, others make themselves felt only during puberty or when a person reaches 30–50 years of age.

Polygenic diseases

These pathologies can be explained not only by genetic predisposition, but also, to a large extent, by external factors (poor nutrition, poor environment, etc.). Polygenic diseases are also called multifactorial. This is justified by the fact that they appear as a result of the actions of many genes. The most common multifactorial diseases include: rheumatoid arthritis, hypertension, coronary heart disease, diabetes mellitus, liver cirrhosis, psoriasis, schizophrenia, etc.

These diseases make up about 92% of the total number of pathologies transmitted by inheritance. With age, the incidence of diseases increases. In childhood, the number of patients is at least 10%, and in the elderly - 25-30%.

To date, several thousand genetic diseases have been described, here is just a short list of some of them:

Some genetic diseases can appear literally in every generation. As a rule, they do not appear in children, but with age. Risk factors (poor environment, stress, hormonal imbalances, poor nutrition) contribute to the manifestation of a genetic error. Such diseases include diabetes, psoriasis, obesity, hypertension, epilepsy, schizophrenia, Alzheimer's disease, etc.

Diagnosis of gene pathologies

Not every genetic disease is detected from the first day of a person’s life; some of them manifest themselves only after several years. In this regard, it is very important to undergo timely research for the presence of gene pathologies. Such diagnostics can be carried out both at the stage of pregnancy planning and during the period of bearing a child.

There are several diagnostic methods:

Biochemical analysis

Allows you to identify diseases associated with hereditary metabolic disorders. The method involves a human blood test, qualitative and quantitative study of other biological fluids of the body;

Cytogenetic method

Identifies the causes of genetic diseases that lie in disturbances in the organization of cellular chromosomes;

Molecular cytogenetic method

An improved version of the cytogenetic method, which makes it possible to detect even microchanges and the smallest chromosome breaks;

Syndromological method

A genetic disease in many cases may have the same symptoms that will coincide with the manifestations of other, non-pathological diseases. The method consists in the fact that with the help of a genetic examination and special computer programs, from the entire spectrum of symptoms, only those that specifically indicate a genetic disease are isolated.

Molecular genetic method

At the moment it is the most reliable and accurate. It makes it possible to study human DNA and RNA and detect even minor changes, including in the nucleotide sequence. Used to diagnose monogenic diseases and mutations.

Ultrasound examination (ultrasound)

To identify diseases of the female reproductive system, ultrasound of the pelvic organs is used. Ultrasound is also used to diagnose congenital pathologies and some chromosomal diseases of the fetus.

It is known that about 60% of spontaneous miscarriages in the first trimester of pregnancy are due to the fact that the fetus had a genetic disease. The mother's body thus gets rid of the non-viable embryo. Inherited genetic diseases can also cause infertility or repeated miscarriages. Often a woman has to undergo many inconclusive examinations until she consults a geneticist.

The best prevention of the occurrence of a genetic disease in the fetus is a genetic examination of the parents during pregnancy planning. Even being healthy, a man or woman can carry damaged gene sections in their genotype. A universal genetic test can detect more than a hundred diseases that are based on gene mutations. Knowing that at least one of the future parents is a carrier of the disorder, the doctor will help you choose adequate tactics for preparing for pregnancy and its management. The fact is that gene changes that accompany pregnancy can cause irreparable harm to the fetus and even become a threat to the life of the mother.

During a woman's pregnancy, with the help of special studies, genetic diseases of the fetus are sometimes diagnosed, which may raise the question of whether it is worth continuing the pregnancy at all. The earliest time for diagnosing these pathologies is the 9th week. This diagnosis is carried out using the safe, non-invasive DNA test Panorama. The test consists of taking blood from a vein from the expectant mother, using the sequencing method to isolate the genetic material of the fetus from it and studying it for the presence of chromosomal abnormalities. The study can identify abnormalities such as Down syndrome, Edwards syndrome, Patau syndrome, microdeletion syndromes, sex chromosome pathologies and a number of other anomalies.

An adult, after passing genetic tests, can find out about his predisposition to genetic diseases. In this case, he will have a chance to resort to effective preventive measures and prevent the occurrence of a pathological condition by being observed by a specialist.

Treatment of genetic diseases

Any genetic disease poses difficulties for medicine, especially since some of them are quite difficult to diagnose. A huge number of diseases cannot be cured in principle: Down syndrome, Klinefelter syndrome, cystic fibrosis, etc. Some of them seriously reduce human life expectancy.

Main methods of treatment:

• Symptomatic

  Relieves symptoms that cause pain and discomfort, prevents the progression of the disease, but does not eliminate its cause.

  geneticist

  Kyiv Yulia Kirillovna

  If you have:

  • questions arose regarding the results of prenatal diagnostics;
  • poor screening results
  we offer you sign up for a free consultation with a geneticist*

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Every healthy person has 6-8 damaged genes, but they do not disrupt cell functions and do not lead to disease, since they are recessive (non-manifest). If a person inherits two similar abnormal genes from his mother and father, he becomes ill. The probability of such a coincidence is extremely low, but it increases sharply if the parents are relatives (that is, they have a similar genotype). For this reason, the incidence of genetic abnormalities is high in closed populations.

Each gene in the human body is responsible for the production of a specific protein. Due to the manifestation of a damaged gene, the synthesis of an abnormal protein begins, which leads to impaired cell function and developmental defects.

A doctor can determine the risk of a possible genetic anomaly by asking you about diseases of relatives “up to the third generation” both on your side and on your husband’s side.

There are a great many genetic diseases, some of which are very rare.

List of rare hereditary diseases

Here are the characteristics of some genetic diseases.

Down syndrome (or trisomy 21)- a chromosomal disease characterized by mental retardation and impaired physical development. The disease occurs due to the presence of the third chromosome in the 21st pair (in total, a person has 23 pairs of chromosomes). It is the most common genetic disorder, affecting approximately one in 700 births. The incidence of Down syndrome increases in children born to women over 35 years of age. Patients with this disease have a special appearance and suffer from mental and physical retardation.

Turner syndrome- a disease that affects girls, characterized by the partial or complete absence of one or two X chromosomes. The disease occurs in one in 3,000 girls. Girls with this condition are usually very short and their ovaries do not function.

X trisomy syndrome- a disease in which a girl is born with three X chromosomes. This disease occurs on average in one in 1000 girls. Trisomy X syndrome is characterized by slight mental retardation and, in some cases, infertility.

Klinefelter syndrome- a disease in which a boy has one extra chromosome. The disease occurs in one boy out of 700. Patients with Klinefelter syndrome, as a rule, are tall and do not have any noticeable external developmental abnormalities (after puberty, facial hair growth is difficult and the mammary glands are slightly enlarged). The intelligence of patients is usually normal, but speech impairments are common. Men suffering from Klinefelter syndrome are usually infertile.

Cystic fibrosis- a genetic disease in which the functions of many glands are disrupted. Cystic fibrosis affects only Caucasian people. About one in 20 white people has one damaged gene that, if present, can cause cystic fibrosis. The disease occurs if a person receives two such genes (from the father and from the mother). In Russia, cystic fibrosis, according to various sources, occurs in one newborn out of 3500-5400, in the USA - in one out of 2500. With this disease, the gene responsible for the production of a protein that regulates the movement of sodium and chlorine through cell membranes is damaged. Dehydration occurs and the viscosity of the gland secretion increases. As a result, a thick secretion blocks their activity. In patients with cystic fibrosis, protein and fat are poorly absorbed, and as a result, growth and weight gain are greatly reduced. Modern treatment methods (taking enzymes, vitamins and a special diet) allow half of patients with cystic fibrosis to live more than 28 years.

Hemophilia- a genetic disease characterized by increased bleeding due to a deficiency of one of the blood clotting factors. The disease is inherited through the female line, and affects the vast majority of boys (on average, one in 8,500). Hemophilia occurs when the genes responsible for the activity of blood clotting factors are damaged. With hemophilia, frequent hemorrhages in the joints and muscles are observed, which can ultimately lead to their significant deformation (that is, to a person’s disability). People with hemophilia should avoid situations that could lead to bleeding. People with hemophilia should not take medications that reduce blood clotting (for example, aspirin, heparin, and some pain relievers). To prevent or stop bleeding, the patient is given a plasma concentrate containing a large amount of the missing coagulation factor.

Tay Sachs disease- a genetic disease characterized by the accumulation of phytanic acid (a product of fat breakdown) in tissues. The disease occurs mainly among Ashkenazi Jews and French Canadians (one in 3,600 newborns). Children with Tay-Sachs disease are delayed in development from an early age, then paralysis and blindness occur. As a rule, patients live up to 3-4 years. There are no treatments for this disease.

Instructions

Today, several thousand genetic diseases are known to be caused by abnormalities in human DNA. Each of us has 6-8 damaged genes, but they do not manifest themselves and do not lead to the development of the disease. If a child inherits two similar abnormal genes from his father and mother, he will get sick. Therefore, future parents try to get an appointment with a geneticist in order to establish with his help the possible risk of a genetic anomaly.

Down syndrome is one of the most common genetic diseases. Babies with one extra chromosome are born with an altered facial structure, decreased muscle tone, and malformations of the digestive and cardiovascular systems. Such children lag behind their peers in development. The syndrome is registered in one child out of 1000 newborns, and you can find out about it already in the second trimester of pregnancy by undergoing prenatal screening.

Cystic fibrosis is most common among people from the Caucasus and. If both parents are carriers of defective genes, the risk of having a baby with dysfunction of the respiratory system, reproductive system and digestive tract increases. The cause of these problems is a deficiency of protein, which is vital for the body, since it controls the balance of chlorides in cells.

Hemophilia is a disease associated with increased bleeding. This disease is inherited through the female line and affects mainly male children. As a result of damage to the genes responsible for blood clotting, hemorrhages occur in the joints, muscles and internal organs, which can lead to their deformation. If such a baby appears in your family, you should know that he should not be given drugs that reduce blood clotting.

Fragile X syndrome, also known as Martin-Bell syndrome, causes the most common type of congenital mental retardation. Both minor and severe developmental delays are observed. The consequences of this disease are often associated with autism. The course of the disease is determined by the number of abnormal repeating regions in the X chromosome: the more there are, the more severe the consequences of the syndrome.

Turner syndrome can only affect your baby if you are carrying a girl. One in 3,000 newborns has a partial or complete absence of one or two X chromosomes. Babies with this disease are very short and have non-functioning ovaries. And if a female child is born with three X chromosomes, a diagnosis of trisomy X syndrome is made, which causes mild mental retardation and, in some cases, infertility.

V.G. Vakharlovsky - medical geneticist, pediatric neurologist of the highest category, candidate of medical sciences. Doctor of the genetic laboratory for prenatal diagnosis of hereditary and congenital diseases of IAH named after. TO. Otta - for more than 30 years he has been engaged in medical and genetic counseling on the prognosis of the health status of children, the study, diagnosis and treatment of children suffering from hereditary and congenital diseases of the nervous system. Author of more than 150 publications.

Each of us, thinking about a child, dreams of having only a healthy and ultimately happy son or daughter. Sometimes our dreams are crushed, and a child is born seriously ill, but this does not mean at all that this dear, blood (scientifically: biological) child in the overwhelming majority of cases will be less loved and less dear. Of course, when a sick child is born, worries, material costs, and stress - physical and moral - arise immeasurably more than when a healthy one is born. Some people condemn a mother and/or father who abandons a sick child. But, as the Gospel tells us: “Judge not and you will not be judged.” They abandon the child for a variety of reasons, both on the part of the mother and/or father (social, material, age, etc.) and the child (severity of the disease, the possibility and prospects of treatment, etc.). So-called abandoned children can be both sick and practically healthy people, regardless of age: both newborns and infants, as well as older ones.

For various reasons, spouses decide to take a child into the family from an orphanage or directly from a maternity hospital. Less often, this, from our point of view, humane, courageous civil act, is done by single women. It happens that disabled children leave the orphanage and their named parents deliberately take into the family a child with an illness or with cerebral palsy, etc.

The purpose of this work is to highlight the clinical and genetic features of the most common hereditary diseases that appear in a child immediately after birth and then, based on the clinical picture of the disease, a diagnosis can be made, or during the subsequent years of the child’s life, when the pathology is diagnosed depending on time the appearance of the first symptoms specific to this disease. Some diseases can be detected in a child even before the appearance of clinical symptoms using a number of laboratory, biochemical, cytogenetic and molecular genetic studies.

The probability of having a child with a congenital or hereditary pathology, the so-called population or general statistical risk, equal to 3-5%, haunts every pregnant woman. In some cases, it is possible to predict the birth of a child with a particular disease and diagnose the pathology already in the prenatal period. Some congenital defects and diseases are diagnosed in the fetus using laboratory-biochemical, cytogenetic and molecular genetic techniques, or more precisely, a set of prenatal (antenatal) diagnostic methods.

We are convinced that all children offered for adoption should be examined in detail by all medical specialists in order to exclude relevant specialized pathologies, including examination and examination by a geneticist. In this case, all known data about the child and his parents must be taken into account.

Chromosomal mutations

In the nucleus of each cell of the human body there are 46 chromosomes, i.e. 23 pairs containing all hereditary information. A person receives 23 chromosomes from the mother with the egg and 23 from the father with the sperm. When these two sex cells merge, the result that we see in the mirror and around us is obtained. The study of chromosomes is carried out by a cytogeneticist. For this purpose, blood cells called lymphocytes are used, which are specially treated. A set of chromosomes, distributed by a specialist into pairs and by serial number - the first pair, etc., is called a karyotype. We repeat, the nucleus of each cell contains 46 chromosomes or 23 pairs. The last pair of chromosomes determines the sex of a person. In girls, these are XX chromosomes, one of them is received from the mother, the other from the father. Boys have XY sex chromosomes. The first is received from the mother and the second from the father. Half of the sperm contain the X chromosome and the other half the Y chromosome.

There is a group of diseases that are caused by changes in the set of chromosomes. The most common of these is Down syndrome (one in 700 newborns). The diagnosis of this disease in a child must be made by a neonatologist in the first 5-7 days of the newborn’s stay in the maternity hospital and confirmed by examining the child’s karyotype. In Down syndrome, the karyotype is 47 chromosomes, the third chromosome is found on the 21st pair. Girls and boys suffer from this chromosomal pathology equally.

Only girls can have Shereshevsky-Turner disease. The first signs of pathology are most often noticeable at the age of 10-12, when the girl has small stature, low-set hair on the back of her head, and at 13-14 years there is no hint of menstruation. There is a slight mental retardation. The leading symptom in adult patients with Shereshevsky-Turner disease is infertility. The karyotype of such a patient is 45 chromosomes. One X chromosome is missing. The incidence of the disease is 1 in 3,000 girls and among girls with a height of 130-145 cm - 73 in 1,000.

Only males experience Kleinfelter's disease, the diagnosis of which is most often made at 16-18 years of age. The patient has a high height (190 cm and above), often a slight mental retardation, long arms disproportionate to the height, covering the chest when circling it. When studying the karyotype, 47 chromosomes are observed - 47, XXY. In adult patients with Kleinfelter's disease, the leading symptom is infertility. The prevalence of the disease is 1: 18,000 healthy men, 1: 95 boys with mental retardation and one among 9 men who are infertile.

Above we have described the most common chromosomal diseases. More than 5,000 diseases of a hereditary nature are classified as monogenic, in which there is a change, a mutation, in any of the 30,000 genes found in the nucleus of a human cell. The work of certain genes contributes to the synthesis (formation) of the protein or proteins corresponding to this gene, which are responsible for the functioning of cells, organs and systems of the body. A disruption (mutation) of a gene leads to disruption of protein synthesis and further disruption of the physiological function of cells, organs and body systems in which the protein is involved. Let's look at the most common of these diseases.