Genes and chromosomes transmitted to the child!!! Genetic diseases that are inherited. Medical genetic examination
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:
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 |
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Change in the structure of chromosomes. | Syndromes of Miller-Dikker, Williams, Langer-Gidion. |
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Change in the number of chromosomes. | Syndromes of Down, Patau, Edwards, Klayfenter. |
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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 genes is increased by physical, chemical and biological properties. Some alkaloids, nitrates, nitrites, some food additives, pesticides, solvents and petroleum products have this property.
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?
The genetic center will help to detect the disease or predisposition to it in time. Usually this is in all major cities. Before taking tests, a consultation with a doctor is held 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. There are many cases when people with a similar syndrome could well lead an independent life, find a job 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.
So, chains in the DNA molecule, called "genes", are responsible for heredity. Mixing the genes of mom and dad from the point of view of biology can be considered a unique genetic experiment. This name was given to the process of the birth of a new life by one of the leading experts in the field of genetics of behavior, American Robert Plomin. In biology, the mystery of conception can be written in the form of a formula, just like the genes and chromosomes passed on to a child: each egg and each sperm cell carries a unique combination of 23 chromosomes. Combining in pairs, the parental chromosomes randomly form the unique genetic code of the future person - the genotype.
Fact
Babies are more like dads. Nature "conceived" so that the man immediately saw himself in the child and the instinct of paternity was formed faster.
For mom or dad?
The child, as a rule, inherits the color of the eyes of the parent, whose eyes are darker. For example, a brown-eyed mother and a blue-eyed father, even if the baby is a father's copy, will most likely have brown eyes.
If one of the parents has curly hair, then the firstborn is likely to have curls too.
Is the first child a boy? Then he will surely look like a mother with the help of the gene and chromosomes transmitted to the child. The girl is for dad. In such cases, they say: "He will be happy."
The mind and ingenuity of the baby inherits from the mother. The latter, by the way, is confirmed by science. The fact is that the genes “responsible” for IQ are located on the X chromosomes, of which women have two (XX), and men have one (XY).
A girl born from a brilliant father is much more likely to be known as a clever woman, but nature will most likely “rest” on the son of a brilliant personality.
The baby will be light-headed "in mother" only if the blondes were also among the father's relatives.
Bad habits are encoded at the genetic level. Alcohol dependence is determined by the gene responsible for the synthesis of an enzyme that breaks down alcohol. If the gene is mutated, then the child of parents who like to drink, there is a tendency to alcoholism.
character by inheritance
The fact that character is inherited with the help of a gene and chromosomes transmitted to a child has not yet been scientifically confirmed. Although the “aggressiveness gene” discovered by scientists a few years ago has already given ground for this kind of talk. True, practical experiments disproved them. And yet it was not in vain that Russian rumor advised to look at the future mother-in-law. How many times have you already said, looking at your daughter: “Well, stubborn - all like a grandfather!” or noticed in the son: "Oh, the character is paternal." Yes, all this can be attributed to the so-called costs of education. The fact that the child unconsciously copies the behavior of the parents, noticing how they behave in a certain situation. Then he repeats the act in similar conditions. Meanwhile, scientists working on deciphering the human genetic code have already established that the tendency to polite or rude behavior is 34% genetically inherent in us. The rest is determined by upbringing and environment. And even the choice of a profession, we owe 40% to a certain combination of chromosomes. At the very least, leadership qualities in most cases are inherited. Perhaps that is why in Russia there was a dynastic principle of transferring royal power - from father to son.
"Neither mother nor father..."
Indeed, it happens that a son or daughter is not at all like their parents. They can easily repeat the genotype of some distant relative. Or very far. And he left this world a long time ago.
The dissimilarity to anyone often worries the father very much. Tell your beloved husband that your child is like your great-great-grandmother or - and he will calm down for a while.
And also look at your husband’s childhood photos, your own and you will see: the appearance of a growing child is constantly changing and in a year or two your crumbs may show a lot of your features.
Geneticist and Ph.D. Dean Hamer first announced the existence of a "homosexual gene" in 1993, and in 2004 wrote a book about the discovery of a "faith in God gene."
British scientists analyzed the nature of 609 pairs of twins and it turned out that if the ability to run one's own business, sociability and introversion were characteristic of one of the brothers, then they were necessarily present in the character of the other. Even such a habit as the desire to sit in front of the TV for a long time is 45% inherited. And scientists have long and seriously argued about the “gene of genius” and the possibility of its isolation, and even its introduction, into the genotype of a particular person. At the same time, the subject of the dispute is the moral component of the issue, and not scientific hypotheses at all. As Sherlock Holmes once said, looking at the portraits of the Baskerville dynasty: “So don’t believe in the transmigration of souls after that!”
Black and striped
Telegony was popular in the 19th century. The theory is that it is not the father's genes that are responsible for the appearance of the crumbs, but the mother's first partner. It arose after an incident that occurred in the world of horses.
One breeder decided to cross a zebra with a mare. She did not want to produce offspring from a stranger. The foals born later from a fellow tribesman turned out to be with zebra stripes.
Scientists believe that intellectual abilities are 50–70% determined by genes, and the choice of profession is 40%. At 34%, we have a tendency to be polite and rude. Even the desire to sit in front of the TV for a long time is 45% a genetic predisposition. The rest, according to experts, is determined by upbringing, social environment and sudden blows of fate - for example, diseases.
A gene, just like an individual organism, is subject to natural selection. If, for example, it allows a person to survive in harsher climates or to endure physical activity longer, it will spread. If, on the contrary, it provides the appearance of some harmful trait, then the prevalence of such a gene in the population will fall.
During the fetal development of a child, this influence of natural selection on individual genes can manifest itself in a rather strange way. For example, genes inherited from the father are "interested" in the rapid growth of the fetus - since the paternal organism obviously does not lose from this, and the child grows faster. Maternal genes, on the other hand, promote slower development—which ends up taking longer, but leaving the mother with more energy.
Prader-Willi syndrome is an example of what happens when mom's genes "win". During pregnancy, the fetus is inactive; after birth, the child has a developmental delay, a tendency to obesity, short stature, drowsiness and impaired coordination of movements. It may seem strange that these apparently unfavorable traits are encoded by maternal genes - but it must be remembered that normally the same genes compete with paternal ones.
In turn, the “victory” of paternal genes leads to the development of another disease: Angelman syndrome. In this case, the child develops hyperactivity, often epilepsy and delayed speech development. Sometimes the patient's vocabulary is limited to just a few words, and even in this case, the child understands most of what is said to him - it is the ability to express his thoughts that suffers.
Of course, it is impossible to predict the appearance of the child. But you can say with a certain degree of certainty what the main features will be. Dominant (strong) and recessive (weak) genes will help us with this.
For each of its external and internal characteristics, the child receives two genes. These genes may be the same (tall, full lips) or different (tall and short, plump and thin). If the genes match, there will be no conflict, and the child inherits full lips and tall stature. Otherwise, the strongest gene wins.
A strong gene is called dominant, and a weak gene is called recessive. Strong genes in humans include dark and curly hair; baldness in men; brown or green eyes; normally pigmented skin. Recessive traits include blue eyes, straight, blond or red hair, and lack of skin pigment.
When a strong and a weak gene meet, the strong one usually wins. For example, mom is brown-eyed brunette, and dad is blond with blue eyes, with a high degree of probability we can say that the baby will be born with dark hair and brown eyes.
True, brown-eyed parents may have a newborn with blue eyes. Thus, the genes received from the grandmother or the grandfather could affect. The opposite situation is also possible. The explanation is that it turns out that not one gene from each parent, as was previously believed, is responsible for any trait, but a whole group of genes. And sometimes one gene is responsible for several functions at once. So a number of genes are responsible for the color of the eyes, which each time are combined in a different way.
Hereditary diseases transmitted by genes
A baby can inherit from his parents not only appearance and character traits, but also diseases (cardiovascular, oncological, diabetes, Alzheimer's and Parkinson's).
The disease may not manifest itself if elementary safety measures are taken. Tell the gynecologist in detail about serious health problems not only for you and your husband, but also for close relatives. This will help protect the baby in the future. Sometimes completely healthy parents give birth to a baby with a hereditary disease. It was laid down in the genes and manifested itself only in the child. This usually happens when both parents have the same disease in their genes. Therefore, if a child is planned, according to experts, it is better to undergo a genetic examination. This is especially true of a family in which children with hereditary diseases were already born.
A weak gene may not be detected in one or many generations until two recessive genes from each parent meet. And then, for example, such a rare sign as albinism may appear.
Chromosomes are also responsible for the sex of the child. For a woman, the chances of giving birth to a girl or a boy are equal. The sex of the child depends only on the father. If an egg meets a sperm with an X sex chromosome, it will be a girl. If U - a boy will be born.
What else can depend on genes:
Gender - 100%;
Height - 80% (for men) and 70% (for women);
Blood pressure - 45%;
Snoring - 42%;
Female infidelity - 41%;
Spirituality - 40%;
Religiosity - 10%.
There are also genes responsible for the development of certain conditions, such as depression or a tendency to uncontrolled eating.
The level of mutations in men is 2 times higher than in women. Thus, it turns out that humanity owes its progress to men.
All representatives of the human race are 99.9% identical in DNA, which completely sweeps aside any basis for racism.
Incredible Facts
Parents love to pretend What will their future child look like?.
Will he inherit his mother's eyes or his father's nose? Are there certain traits we get from each parent?
Genetics is an interesting and very complex thing. A child receives 23 chromosomes from the mother and 23 from the father, and there are many options for how they will be combined and what the end result will be.
Although the genetic influence is generally equal on the part of both parents, many scientists conclude that father is sometimes more influential than mother.
1. Eye color
Dark eye colors such as brown and black are dominant, while light eye colors such as blue are recessive.
Usually the child inherits the dominant eye color of the parents. For example, if dad has brown eyes and mom has blue eyes, then the child is likely to be brown-eyed.
But this is not always the case. If the father has a recessive eye color, such as blue or green, the child is more likely to inherit the father's eye color.
2. Dimples on the cheeks
What could be cuter than dimples, and if your father had dimples, chances are high that the child will be born with the same cute dimples.
Cheek dimples are a dominant feature, and their appearance is associated with the location of the muscles on the face.
3. Fingerprint pattern
Each person has their own unique fingerprints, and they are not repeated in parents and children. However, there is a genetic predisposition towards fingerprints.
The prints of fathers and children, though never the same, are very similar. Look at the hands of a child and you will see similar curls or arches in the father.
4. Symmetry of the face
Genetics play a big role in what facial features or the ratio of these traits your children will have.
Children tend to inherit the facial symmetry of the father and if, looking at your son or daughter, you clearly see his father, then there is a reason for this.
5. Child growth
The growth of the child is influenced by the genes of both parents, however father plays a big role in how tall or short a child will be. If the father is tall, then the children will also be tall, maybe not as tall as the father, if the mother is short, but nonetheless.
6. Baby's weight
Weight is largely determined by genetics, and there is a relationship between the weight of the parents, especially the father, and the weight of the children when they grow up.
It's interesting that father's weight may affect birth weight of baby. So, if the father's genes are expressed during pregnancy and intrauterine development of the child, then the mother's genes can be suppressed to some extent.
7. Hair
As with the eyes, dominant and recessive genes have a big impact on hair color.
Dark hair is dominant, and if your father has dark hair, then yours is likely to be dark too.
Moreover, the father's genes play a decisive role in what will be the texture of the baby's hair. If the father has curly hair, then it is unlikely that the child will have straight hair.
8. Lips
As for the shape and size of the lips, the father's genes can significantly affect this trait. Full lips are a dominant feature, and if the father has full lips, then the child is also likely to have full lips.
9. Dental problems
Unfortunately or fortunately, the structure of the teeth, as well as the problems associated with them, is a hereditary trait. If the father had bad teeth, then the child will probably have to face problems too.
Did you know that there is gene responsible for gaps between teeth? If your father had a gap between his teeth, don't be surprised if you inherit one.
10. Risk-taking
If a father likes to take risks, then this can leave an imprint on the personality of future children. It is believed that a person's personality is to some extent predetermined from birth.
So, for example, there is a gene responsible for the search for novelty and inclining a person to risky behavior. A person who is adventurous most likely inherited this feature from his father.
11. Sense of humor
Although there is no specific gene responsible for sense of humor, there is a set of genes that determine the tendency to wit.
Of course, a sense of humor is a social trait, and if parents like to play pranks on each other and laugh, then the child will also be funny.
12. Intelligence
The potential of the child's intelligence is also determined to a greater extent by genetics, namely the intelligence of the father.