Hereditary diseases in women. Genetic diseases - some of the most common diseases

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

Genetic diseases humans 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 noticeable already 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, external factors (poor nutrition, bad 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, ischemic disease hearts, diabetes, liver cirrhosis, psoriasis, schizophrenia, etc.

These diseases account for about 92% of total number 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, violations hormonal levels, 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 women reproductive system use ultrasound of the pelvic organs. For diagnostics congenital pathologies and some fetal chromosomal diseases also use ultrasound.

It is known that about 60% 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 genetic testing 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. Most early date diagnosis of these pathologies – 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, having passed genetic tests, can learn 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 pathological condition, 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

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Content

During his life, a person suffers from many mild or severe diseases, but in some cases he is born with them. Hereditary diseases or genetic disorders appear in a child due to a mutation in one of the DNA chromosomes, which leads to the development of the disease. Some of them only carry external changes, but there are a number of pathologies that threaten the baby’s life.

What are hereditary diseases

These are genetic diseases or chromosomal abnormalities, the development of which is associated with a disorder in the hereditary apparatus of cells transmitted through reproductive cells (gametes). The occurrence of such hereditary pathologies is associated with the process of transmission, implementation, storage genetic information. More and more men have problems with this type of deviation, so the chance of conceiving healthy child is getting smaller. Medicine is constantly researching to develop a procedure for preventing the birth of children with disabilities.

Causes

Genetic diseases of hereditary type are formed by mutation of genetic information. They can be detected immediately after the birth of a child or after a long time during the long development of the pathology. There are three main reasons for the development of hereditary diseases:

• chromosomal abnormalities;
• chromosome disorders;
• gene mutations.

The last reason is included in the group of hereditarily predisposed type, because their development and activation are also influenced by factors external environment. A striking example of such diseases is considered hypertonic disease or diabetes. In addition to mutations, their progression is affected by prolonged overexertion nervous system, poor nutrition, mental trauma and obesity.

Symptoms

Each hereditary disease has its own specific symptoms. At the moment, over 1600 are known various pathologies, which cause genetic and chromosomal abnormalities. Manifestations vary in severity and brightness. To prevent the onset of symptoms, it is necessary to identify the likelihood of their occurrence in time. The following methods are used for this:

1. Twin. Hereditary pathologies are diagnosed by studying the differences and similarities of twins to determine the influence of genetic characteristics and the external environment on the development of diseases.
2. Genealogical. The likelihood of developing abnormal or normal traits is studied using a person's pedigree.
3. Cytogenetic. The chromosomes of healthy and sick people are studied.
4. Biochemical. Human metabolism is monitored and the features of this process are highlighted.

In addition to these methods, most girls undergo ultrasonography. It helps determine, based on fetal characteristics, the likelihood of birth defects development (from the 1st trimester), assume the presence of a certain number of chromosomal diseases or hereditary ailments of the nervous system in the unborn child.

In children

The vast majority of hereditary diseases appear in childhood. Each of the pathologies has its own symptoms that are unique to each disease. Anomalies a large number of, so they will be described in more detail below. Thanks to modern diagnostic methods, it is possible to identify abnormalities in a child’s development and determine the likelihood of hereditary diseases even while the child is pregnant.

Classification of hereditary human diseases

Genetic diseases are grouped based on their occurrence. The main types of hereditary diseases are:

1. Genetic – arise from DNA damage at the gene level.
2. Hereditary predisposition, autosomal recessive diseases.
3. Chromosomal abnormalities. Diseases arise due to the appearance of an extra chromosome or the loss of one of the chromosomes or their aberrations or deletions.

List of hereditary human diseases

Science knows more than 1,500 diseases that fall into the categories described above. Some of them are extremely rare, but certain types heard by many. The most famous pathologies include the following:

• Albright's disease;
• ichthyosis;
• thalassemia;
• Marfan syndrome;
• otosclerosis;
• paroxysmal myoplegia;
• hemophilia;
• Fabry disease;
• muscular dystrophy;
• Klinefelter's syndrome;
• Down syndrome;
• Shereshevsky-Turner syndrome;
• cat cry syndrome;
• schizophrenia;
• congenital hip dislocation;
• heart defects;
• cleft palate and lip;
• syndactyly (fusion of fingers).

Which are the most dangerous?

Of the pathologies listed above, there are those diseases that are considered dangerous to human life. As a rule, this list includes those anomalies that have polysomy or trisomy in the chromosome set, when instead of two there are from 3 to 5 or more. In some cases, 1 chromosome is detected instead of 2. All such anomalies are the result of deviations in cell division. With this pathology, a child lives up to 2 years; if the deviations are not very serious, then he lives up to 14 years. The most dangerous ailments are:

• Canavan disease;
• Edwards syndrome;
• hemophilia;
• Patau syndrome;
• spinal muscular amyotrophy.

Down syndrome

The disease is inherited when both or one of the parents has defective chromosomes. Down syndrome develops due to trisomy 21 chromosomes (instead of 2 there is 3). children with this disease suffer from strabismus, have abnormally shaped ears, a fold on the neck, and mental retardation and heart problems. This chromosome abnormality is not life-threatening. According to statistics, 1 out of 800 is born with this syndrome. Women who want to give birth after 35, the probability of having a child with Down increases (1 in 375); after 45 years, the probability is 1 in 30.

Acrocraniodysphalangia

The disease has an autosomal dominant type of inheritance of the anomaly, the cause is a violation in chromosome 10. Scientists call the disease acrocraniodysphalangia or Apert syndrome. Characterized by the following symptoms:

• violations of the ratio of the length and width of the skull (brachycephaly);
• increased growth is formed inside the skull blood pressure(hypertension) due to fusion of coronary sutures;
• syndactyly;
• mental retardation due to compression of the brain by the skull;
• prominent forehead.

What are the treatment options for hereditary diseases?

Doctors are constantly working on the problem of gene and chromosome abnormalities, but all treatment is limited at this stage comes down to suppressing symptoms, full recovery fails to achieve. Therapy is selected depending on the pathology in order to reduce the severity of symptoms. The following treatment options are often used:

1. Increasing the amount of incoming coenzymes, for example, vitamins.
2. Diet therapy. An important point that helps to get rid of a number of unpleasant consequences of hereditary anomalies. If the diet is violated, it is immediately observed sharp deterioration patient status. For example, with phenylketonuria, foods that contain phenylalanine are completely excluded from the diet. Refusal of this measure can lead to severe idiocy, so doctors focus on the need for diet therapy.
3. Consumption of those substances that are absent in the body due to the development of pathology. For example, for orotaciduria, cytidylic acid is prescribed.
4. In case of metabolic disorders, it is necessary to ensure timely cleansing of the body from toxins. Wilson-Konovalov disease (copper accumulation) is treated with d-penicillamine, and hemoglobinopathy (iron accumulation) is treated with desferal.
5. Inhibitors help block excessive enzyme activity.
6. It is possible to transplant organs, tissue sections, and cells that contain normal genetic information.

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 W E Y Z All sections Hereditary diseases Emergency conditions Eye diseases Children's diseases Men's diseases Sexually transmitted diseases Women's diseases Skin diseases Infectious diseases Nervous diseases Rheumatic diseases Urological diseases Endocrine diseases Immune diseases Allergic diseases Oncological diseases Diseases of veins and lymph nodes Hair diseases Dental diseases Blood diseases Breast diseases Diseases of the respiratory tract and injuries Diseases of the respiratory system Diseases of the digestive system Diseases of the heart and blood vessels Diseases of the large intestine Diseases of the ear, nose and throat Drug problems Mental disorders Speech disorders Cosmetic problems Aesthetic problems

Hereditary diseases – large group human diseases caused 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 genetic factors, 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 during different stages 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. Most severe forms hereditary pathologies of the fetus 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 diseases metabolism (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 identified using cytogenetic, molecular genetic, and biochemical research methods.

Unfortunately, complete cure hereditary diseases are 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 wide range 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.

Possibilities surgical treatment hereditary diseases come down mainly to the elimination of severe developmental defects 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.

Today, gynecologists advise all women to plan their pregnancy. After all, in this way you can avoid many hereditary diseases. This is possible with a thorough medical examination of both spouses. There are two points regarding the issue of hereditary diseases. The first is a genetic predisposition to certain diseases, which manifests itself as the child grows up. For example, diabetes mellitus, which one of the parents suffers from, can manifest itself in children in adolescence, and hypertension - after 30 years. The second point is the direct genetic diseases with which the child is born. We will talk about them today.

The most common genetic diseases in children: description

The most common hereditary disease in children is Down syndrome. It occurs in 1 case out of 700. The diagnosis of the child is made by a neonatologist while the newborn is in the maternity hospital. In Down syndrome, the child's karyotype contains 47 chromosomes, that is, the extra chromosome is the cause of the disease. You should know that both girls and boys are equally susceptible to this chromosomal pathology. Visually, these are children with a specific facial expression who are lagging behind in mental development.

Girls are more often affected by Shereshevsky-Turner disease. And the symptoms of the disease appear at the age of 10-12: patients are short in stature, the hair on the back of the head is low-set, and at the age of 13-14 they do not experience puberty and no periods. These children show a slight delay mental development. The leading symptom of this hereditary disease in adult woman is infertility. The karyotype for this disease is 45 chromosomes, that is, one chromosome is missing. The prevalence rate of Shereshevsky-Turner disease is 1 case in 3000. And among girls up to 145 centimeters tall, it is 73 cases in 1000.

Only male characterized by Kleinfelter's disease. This diagnosis is established at the age of 16-18 years. Signs of the disease - high growth (190 centimeters and even higher), mild mental lag, disproportionate Long hands. The karyotype in this case is 47 chromosomes. A characteristic symptom for an adult man is infertility. Kleinfelter's disease occurs in 1 in 18,000 cases.

Manifestation is enough known disease- hemophilia - usually observed in boys after one year of life. The pathology mainly affects representatives strong half humanity. Their mothers are only carriers of the mutation. Bleeding disorders are the main symptom of hemophilia. This often leads to the development of severe joint damage, for example, hemorrhagic arthritis. In hemophilia, any injury that cuts the skin causes bleeding, which can be fatal for a man.

Another hard one hereditary disease- cystic fibrosis. Typically, children under one and a half years of age need to be diagnosed to detect this disease. Its symptoms are chronic inflammation of the lungs with dyspeptic symptoms in the form of diarrhea, followed by constipation and nausea. The incidence of the disease is 1 case in 2500.

Rare hereditary diseases in children

There are also genetic diseases that many of us have never heard of. One of them appears at the age of 5 years and is called Duchenne muscular dystrophy.

The carrier of the mutation is the mother. The main symptom of the disease is the replacement of skeletal-striated muscles with connective tissue incapable of contraction. Such a child will eventually face complete immobility and death in the second decade of life. Not for today effective therapy Duchenne muscular dystrophy, despite many years of research and the use of genetic engineering.

Another rare genetic disease is osteogenesis imperfecta. This is a genetic pathology of the musculoskeletal system, which is characterized by bone deformation. Osteogenesis is characterized by a decrease in bone mass and increased fragility. There is an assumption that the cause of this pathology lies in a congenital disorder of collagen metabolism.

Progeria is a fairly rare genetic defect that results in premature aging of the body. There are 52 cases of progeria recorded worldwide. Up to six months, children are no different from their peers. Then their skin begins to become wrinkled. The body manifests itself senile symptoms. Children with progeria usually do not live beyond the age of 15. The disease is caused by gene mutations.

Ichthyosis is a hereditary skin disease that occurs as a dermatosis. Ichthyosis is characterized by a violation of keratinization and manifests itself as scales on the skin. The cause of ichthyosis is also a gene mutation. The disease occurs in one case in several tens of thousands.

Cystinosis is a disease that can turn a person into stone. The human body accumulates too much cystine (an amino acid). This substance turns into crystals, causing hardening of all cells in the body. The man gradually turns into a statue. Typically, such patients do not live to see their 16th birthday. The peculiarity of the disease is that the brain remains intact.

Cataplexy is a disease that has strange symptoms. At the slightest stress, nervousness, nervous tension suddenly all the muscles of the body relax - and the person loses consciousness. All his experiences end in fainting.

Another strange thing rare disease- extrapyramidal system syndrome. The second name of the disease is the dance of St. Vitus. Its attacks overtake a person suddenly: his limbs and facial muscles twitch. As it develops, extrapyramidal system syndrome causes changes in the psyche and weakens the mind. This disease is incurable.

Acromegaly has another name - gigantism. The disease is characterized by high human stature. And the disease is caused by excessive production of the growth hormone somatotropin. The patient always suffers from headaches and drowsiness. Acromegaly today also has no effective treatment.

All these genetic diseases are difficult to treat, and more often they are completely incurable.

How to identify a genetic disease in a child

The level of modern medicine makes it possible to prevent genetic pathologies. To do this, pregnant women are asked to undergo a series of studies to determine heredity and possible risks. In simple words, genetic tests done to identify the future baby’s tendency to hereditary diseases. Unfortunately, statistics record an increasing number of genetic abnormalities in newborn children. And practice shows that most genetic diseases can be avoided by treating them before pregnancy or by terminating a pathological pregnancy.

Doctors emphasize that the ideal option for future parents is to test for genetic diseases at the stage of pregnancy planning.

In this way, the risk of transmitting hereditary disorders to the future baby is assessed. To do this, a couple planning a pregnancy is advised to consult a geneticist. Only the DNA of future parents allows us to assess the risks of giving birth to children with genetic diseases. In this way, the overall health of the unborn child is predicted.

The undoubted advantage of genetic analysis is that it can even prevent miscarriage. But, unfortunately, according to statistics, women most often resort to genetic testing after a miscarriage.

What influences the birth of unhealthy children

So, genetic tests allow us to assess the risks of having unhealthy children. That is, a geneticist can state that the risk of having a baby with Down syndrome, for example, is 50 to 50. What factors influence the health of the unborn child? Here they are:

1. Age of parents. With age genetic cells more and more “breakdowns” are accumulating. This means that the older the father and mother, the higher the risk of having a baby with Down syndrome.
2. Close relationship of parents. Both first and second cousins ​​are more likely to carry the same diseased genes.
3. The birth of sick children to parents or direct relatives increases the chances of having another baby with genetic diseases.
4. Chronic diseases of a familial nature. If both dad and mom are suffering, for example, multiple sclerosis, then the probability of illness and the future baby is very high.
5. Parents' belonging to certain ethnic groups. For example, Gaucher disease, manifested by lesions bone marrow and dementia, more often among Ashkenazi Jews, Wilson's disease - among the peoples of the Mediterranean.
6. Unfavorable external environment. If future parents live near a chemical plant, a nuclear power plant, or a cosmodrome, then polluted water and air contribute to gene mutations in children.
7. Exposure to radiation on one of the parents also increases the risk of gene mutations.

So, today, future parents have every chance and opportunity to avoid the birth of sick children. A responsible attitude towards pregnancy and its planning will allow you to fully experience the joy of motherhood and fatherhood.

Especially for - Diana Rudenko

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, genetic diseases that are inherited occur.

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 transmitted by inheritance have a huge number of 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:

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

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

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.

Risk of occurrence specific 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, a short neck and lack of muscle tone. Ears, as a rule, small, the eye shape is oblique, irregular shape skulls

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.