Diseases transmitted from father to child. How diseases are inherited

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

Mechanisms of heredity

Before talking about diseases, it is worth understanding what 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.

Fragments of the DNA chain are called genes. Each gene contains integral information about one or more traits 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 disturbed, genetic diseases are inherited.

DNA is organized into 46 chromosomes or 23 pairs, one of which is sexual. Chromosomes are responsible for the activity of genes, their copying, as well as repair in case of damage. As a result of fertilization, each pair has one chromosome from the father and the other from the mother.

In this case, one of the genes will be dominant, and the other recessive or suppressed. Simply put, if the gene responsible for eye color is dominant in the father, then the child will inherit this trait from him, and not from the mother.

Genetic diseases

Hereditary diseases occur when abnormalities or mutations occur in the mechanism for storing and transmitting genetic information. An organism whose gene is damaged will pass it on to its offspring 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 declare themselves to the owner. Diabetes mellitus, obesity, psoriasis, Alzheimer's disease, schizophrenia and other disorders are manifested with extremely high frequency.

Classification

Genetic diseases that are inherited have a huge number of varieties. To separate them into separate groups, the location of the disorder, causes, clinical picture, and the nature of heredity can be taken into account.

Diseases can be classified according to the type of inheritance and the 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. Allocate diseases:

• Autosomal dominant - brachydactyly, arachnodactyly, ectopia of the lens.
• Autosomal recessive - albinism, muscular dystonia, dystrophy.
• Sex-limited (observed only in women or men) - hemophilia A and B, color blindness, paralysis, phosphate diabetes.

The quantitative and qualitative classification of hereditary diseases distinguishes gene, chromosomal and mitochondrial types. The latter refers to DNA disturbances in mitochondria outside the nucleus. The first two occur in DNA, which is located 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 the mutation. It occurs quite rarely, about 1 time in a million cases, and is transmitted to descendants if it occurs in germ cells. For individual genes, the mutation rate is 1:108.

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

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

Among the physical factors are ionizing and radioactive radiation, ultraviolet rays, excessively high and low temperatures. The biological causes are rubella viruses, measles, antigens, etc.

genetic predisposition

Parents influence us not only by education. It is known that some people are more likely to develop certain diseases than others due to heredity. A genetic predisposition to diseases occurs when one of the relatives has an abnormality in the 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 race of the person and on the degree of relationship with the patient.

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

How to identify the disease?

Early detection of a disease or predisposition to it will help genetic center. Usually this is in all major cities. Before taking the tests, a consultation is held with the doctor to find out what health problems are observed in relatives.

Medico-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 of the child, affect life expectancy. Most of them are difficult to treat, and their manifestation is only corrected by medical means. 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.

Among the main symptoms are a flattened face, raised corners of the eyes, a short neck, and a lack of muscle tone. The auricles are usually small, the incision of the eyes is oblique, the irregular shape of the skull.

In sick children, concomitant disorders and diseases are observed - pneumonia, SARS, etc. Exacerbations may occur, for example, hearing loss, vision loss, hypothyroidism, heart disease. With Downism, it is slowed down and often remains at the level of seven years.

Constant work, special exercises and preparations significantly improve the situation. Many cases are known when people with a similar syndrome could well 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 is not treated 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 bruise.

Queen Victoria of England was a carrier of hemophilia. She passed on the disease 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 "Petrushka syndrome", as patients have frequent outbursts of laughter and smiles, chaotic hand movements. With this anomaly, a violation of sleep and mental development is characteristic.

The syndrome occurs once in 10,000 cases due to the absence of certain genes in the long arm of the 15th chromosome. Angelman's disease develops only if the 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 cured completely, but it is possible to alleviate the manifestation of symptoms. For this, physical procedures and massages are carried out. Patients do not become completely independent, but during treatment they can serve themselves.

Not only external signs, but also diseases can be inherited. Failures in the genes of ancestors lead, as a result, to consequences in the offspring. We will talk about the seven most common genetic diseases.

Hereditary properties are passed on to descendants from ancestors in the form of genes combined into blocks called chromosomes. All cells of the body, with the exception of the sex cells, have a double set of chromosomes, half of which comes from the mother, and the second part from the father. Diseases, which are caused by certain failures in the genes, are hereditary.

Myopia

Or myopia. A genetically determined disease, the essence of which is that the image is formed not on the retina, but in front of it. The most common cause of this phenomenon is considered to be an enlarged eyeball. As a rule, myopia develops during adolescence. At the same time, a person sees well near, but sees poorly at a distance.

If both parents are nearsighted, then the risk of developing myopia in their children is over 50%. If both parents have normal vision, then the probability of developing myopia is no more than 10%.

Researching myopia, the staff of the Australian National University in Canberra came to the conclusion that myopia is inherent in 30% of Caucasians and affects up to 80% of Asians, including residents of China, Japan, South Korea, etc. Having collected data from more than 45 thousand people, scientists have identified 24 genes associated with myopia, and also confirmed their connection with two previously established genes. All these genes are responsible for the development of the eye, its structure, signaling in the tissues of the eye.

Down syndrome

The syndrome, named after the English physician John Down, who first described it in 1866, is a form of chromosomal mutation. Down syndrome affects all races.

The disease is a consequence of the fact that not two, but three copies of the 21st chromosome are present in the cells. Geneticists call this trisomy. In most cases, the extra chromosome is passed on to the child from the mother. It is generally accepted that the risk of having a child with Down syndrome depends on the age of the mother. However, due to the fact that, in general, they are most often given birth in youth, 80% of all children with Down syndrome are born to women under the age of 30 years.

Unlike genes, chromosomal abnormalities are random failures. And in a family there can be only one person suffering from such a disease. But even here there are exceptions: in 3-5% of cases, there are more rare - translocation forms of Down syndrome, when the child has a more complex structure of the set of chromosomes. A similar variant of the disease can be repeated in several generations of the same family.
According to the Downside Up charity foundation, about 2,500 children with Down syndrome are born in Russia every year.

Klinefelter syndrome

Another chromosomal disorder. Approximately for every 500 newborn boys, there is one with this pathology. Klinefelter's syndrome usually appears after puberty. Men suffering from this syndrome are infertile. In addition, they are characterized by gynecomastia - an increase in the mammary gland with hypertrophy of the glands and adipose tissue.

The syndrome got its name in honor of the American physician Harry Klinefelter, who first described the clinical picture of the pathology in 1942. Together with endocrinologist Fuller Albright, he found that if women normally have a pair of XX sex chromosomes, and men have XY, then with this syndrome, men have from one to three additional X chromosomes.

color blindness

Or color blindness. It is hereditary, much less often acquired. It is expressed in the inability to distinguish one or more colors.
Color blindness is associated with the X chromosome and is transmitted from the mother, the owner of the “broken” gene, to her son. Accordingly, up to 8% of men and no more than 0.4% of women suffer from color blindness. The fact is that in men, “marriage” in a single X chromosome is not compensated, since they do not have a second X chromosome, unlike women.

Hemophilia

Another disease inherited by sons from mothers. The story of the descendants of the English Queen Victoria from the Windsor dynasty is widely known. Neither she nor her parents suffered from this serious disease associated with impaired blood clotting. Presumably, the gene mutation occurred spontaneously, due to the fact that Victoria's father at the time of her conception was already 52 years old.

Children inherited the “fatal” gene from Victoria. Her son Leopold died of hemophilia at 30, and two of her five daughters, Alice and Beatrice, carried the ill-fated gene. One of the most famous descendants of Victoria who suffered from hemophilia is the son of her granddaughter, Tsarevich Alexei, the only son of the last Russian Emperor Nicholas II.

cystic fibrosis

A hereditary disease that manifests itself in disruption of the external secretion glands. It is characterized by increased sweating, secretion of mucus that accumulates in the body and prevents the child from developing, and, most importantly, prevents the full functioning of the lungs. Possible death due to respiratory failure.

According to the data of the Russian branch of the American chemical and pharmaceutical corporation Abbott, the average life expectancy of patients with cystic fibrosis in European countries is 40 years, in Canada and the USA - 48 years, in Russia - 30 years. Famous examples include the French singer Gregory Lemarchal, who died at 23. Presumably, Frederic Chopin also suffered from cystic fibrosis, who died as a result of lung failure at the age of 39.

A disease mentioned in ancient Egyptian papyri. A characteristic symptom of migraine is episodic or regular severe attacks of headache in one side of the head. The Roman physician of Greek origin Galen, who lived in the 2nd century, called the disease hemicrania, which translates as "half of the head." From this term came the word "migraine". In the 90s. In the twentieth century, it was found that migraine is predominantly due to genetic factors. A number of genes responsible for the transmission of migraine by inheritance have been discovered.

When collecting an anamnesis, doctors often ask questions about the presence of certain diseases in the next of kin. This is not idle curiosity, but a completely justified interest, since many pathologies can be inherited. So, knowing what exactly the members of one family faced, it is possible to predict the risk of developing a particular pathology and take preventive measures in time. What kind of problems encountered in the family become dangerous and how to avoid their development - in the material AiF.ru.

Related oncology

Cancer problems are often hereditary, especially tumors in the breast, ovaries, or intestines. According to doctors, if there was one carrier of pathology in the family, you should be wary, and if there are two of them, it is necessary to be examined! In addition, it is necessary to take into account the age at which the parents had a problem. So, for example, the likelihood of developing tumors in a daughter increases if the mother's problems were detected before the onset of menopause - in this case, with a high degree of probability, it is a matter of gene mutation. Why is it easier for several of its members to get a similar pathology within the same family? The genus inherits approximately the same set of genes in structure with slight differences. This means that the problem can easily arise in the same areas.

There is only one way out in this situation - to consult doctors on time and regularly and take tests. So, it is recommended to visit a gynecologist, endocrinologist, oncologist-mammologist and proctologist.

dental question

Members of the same family may have the same problems in the oral cavity. So, if the mother has caries, the child will inherit it with a probability of 45%. Gum disease is inherited in one third of cases. Doctors advise people with a similar predisposition to visit the dentist as often as possible and observe a hygiene regimen - brush your teeth at least 2 times a day, use a mouthwash, use dental floss and an irrigator.

One headache!

70-80% - this is the risk of inheriting such an unpleasant disease as migraine. Scientists have determined that there is a gene that causes pathology, if it does not work properly, any irritating factors can easily become a launch catalyst unpleasant symptoms. In addition, in family relationships, the features of the vascular structure are quite similar. This means that the risk of developing the disease in the same way as that of the mother increases markedly.

If there are all the risks of developing such a pathology, it is necessary to reconsider your diet, excluding from it the traditionally dangerous foods that provoke migraine attacks. These include chocolate, cheeses, coffee, citrus fruits and red wine. Often the cause of the start of the disease are hormonal fluctuations.

Grandma's Arthritis

Rheumatoid arthritis and osteoarthritis, which is directly related to the inflammatory process, lead to joint deformity. Moreover, such diseases are often inherited. The number of generations through which they can be transmitted has not yet been precisely established. It should be borne in mind that additional catalysts for the development of pathology are bad habits, excess weight, lack of movement.

In order to prevent the development of the problem, it is necessary to engage in physical education and follow the principles healthy eating which will keep your joints healthy for longer.

Mom's heart

Doctors are sure that if heart problems are found in the mother before the age of 65, and in the father before the age of 50, the risk of the child repeating their fate ranges from 25-50%. Naturally, this is only a hereditary risk. But it is often aggravated by other factors: malnutrition, lack of physical activity, etc. In order to avoid problems, you should correctly build your nutrition schedule, choose a diet, refuse bad habits and include more activity in your life. And of course, regular visits to the cardiologist will not be superfluous.

Inherited diseases are not at all like inheritance in the form of a stake in Gazprom, an apartment in the center of Moscow, or an album with yellowed and faded photographs. During the transmission of hereditary diseases, no one dies, but sometimes the heir is not at all sweet. And to refuse such an inheritance will not work, unfortunately ...

What is it, diseases that are inherited?

Hereditary and congenital diseases

Hereditary, genetic and congenital diseases are not synonymous with the same problem, although, from a mathematical point of view, these sets overlap. Congenital diseases may or may not be hereditary. Hereditary diseases can be gene, chromosomal and mitochondrial.

Gene diseases that are inherited can be associated with a point violation of the gene structure, or with a more massive mutation. Violation of the structure or loss of part of the chromosome causes chromosomal hereditary diseases. Diseases associated with a point or gross and extensive disruption of the structure of mitochondrial DNA are called mitochondrial hereditary diseases.

In addition, there is the concept of "hereditary predisposition." This may be due, for example, to structural features of the body that increase the risk of developing flat feet or deforming coxarthrosis of the hip joint.

Are there many hereditary diseases in the world?

The list of inherited diseases includes more than 6000 nosological units. The most well-known hereditary diseases include:

• Down syndrome associated with the presence of an extra chromosome: in 21 pairs there are three instead of two.
• Cystic fibrosis associated with a defect in the CFTR gene, resulting in impaired synthesis of one of the proteins and respiratory function.
• Diabetes mellitus, transmitted with an autosomal recessive gene.
• Sickle cell anemia, inherited in the same way as diabetes.
• Color blindness associated with a violation of the perception of color.
• Hemophilia, which affects only men, and the defective gene is transmitted through the maternal line.
• Duchenne myopathy, also inherited through the female line mainly by sons.
• Migraine, the risk of inheritance of which approaches 80%.
• Dwarfism, or achondroplasia. The disease is transmitted with a dominant autosomal gene, that is, if one parent is a dwarf, then the risk of having a child with the same problem is 50%; if both parents are carriers of the mutated gene, then the probability of having a dwarf child increases to 75%.
• Split palate syndrome, or "cleft palate", in which the palatine bones of the skull remain severed. The mechanism of inheritance of this pathology is associated with the action of several recessive genes at once.

Viral hepatitis includes A, B, C, D, E. Once in the human body, they cause acute viral hepatitis, and it can be asymptomatic. Viruses B, C and D can cause chronic liver damage.

What hepatitis can be dangerous for a child. Throughout pregnancy, the risk of miscarriage and premature birth may persist. There is a risk of bleeding during childbirth and the postpartum period. The risk of infection of the child increases if a woman develops hepatitis in the third trimester or if the placenta is damaged. Most often, a child becomes infected with hepatitis during the passage of the birth canal.

As a preventive measure, such children are vaccinated with hyperimmune gamma globulin. Women with chronic hepatitis A can only pass it on to their baby during the birth process. At the same time, it is also possible breast-feeding if the newborn has no damage to the oral mucosa.

Toxoplasmosis

Doctors in the antenatal clinic love to scare this "feline infection" very much. Although 70% of women have antibodies to this infection. Toxoplasmosis is dangerous only if the infection occurs directly during pregnancy. Infection long before pregnancy does not affect the unborn baby. During the waiting period, take precautions when interacting with the cat. Wash your hands after playing with it, wash the tray only with rubber gloves.

Herpes

The herpes virus is of two types - the first type affects the respiratory organs, the second - the genitals. Moreover, if you have never had symptoms of herpes, this does not mean that it is not in the body. Pregnancy is often the very mechanism that triggers the disease.

Intrauterine infection of the child occurs precisely with herpes of the second type. Most often, infection occurs if the exacerbation of herpes occurred precisely in childbirth. During pregnancy, women at risk for infection should monitor the dynamics of changes in the number of antibodies.

Cytomegalovirus

Cytomegalovirus infection also hides in the body asymptomatically. The only thing that can give it away is a sudden decrease in immunity. For a future baby, a cytomegalovurus infection can be dangerous if the mother has become infected with it while already pregnant. Signs of a child's infection can be diagnosed on ultrasound (enlarged spleen and liver) and in a blood test for the presence of antibodies.

Rubella

Rubella is perhaps the most dangerous infection for an unborn child. If a woman has already had rubella, she is not at risk of re-infection and does not affect the fetus in any way. Rubella is easier to prevent than to treat. Therefore, it is necessary to vaccinate in a timely manner (it is absolutely impossible to vaccinate during pregnancy) and avoid places where the disease spreads (often this is a kindergarten).

If there is a suspicion of contact with a patient with rubella, it is imperative to donate blood for the determination of anti-rubella antibodies. Even if antibodies are not detected, it is necessary to do a second test after three weeks. If, on re-analysis, antibodies appear, rubella can be diagnosed.