Type of inheritance is autosomal dominant. Types of inheritance of traits in humans

All the characteristic signs of our body are manifested under the influence of genes. Sometimes only one gene is responsible for this, but more often it happens that several units of heredity are responsible for the manifestation of one or another characteristic.

It has been scientifically proven that for a person the manifestation of such signs as skin color, hair, eyes, degree of mental development, depends on the activity of many genes at once. This inheritance does not exactly follow the laws of Mendel, but goes far beyond its limits.

The study of human genetics is not only interesting, but also important in terms of understanding the inheritance of various hereditary diseases. Now, the treatment of young couples in genetic counseling is becoming quite urgent, so that, after analyzing the pedigree of each spouse, it could be confidently asserted that the baby will be born healthy.

Types of inheritance of traits in humans

If you know how a particular trait is inherited, then you can predict the probability of its manifestation in the offspring. All the signs in the body can be divided into dominant and recessive. Interaction between them is not so simple, and at times it is not enough to know which one belongs to which category.

Now in the scientific world, there are the following types of inheritance in humans:

1. Monogenic inheritance.
2. Polygenic.
3. Unconventional.

These types of inheritance, in turn, are also subdivided into some varieties.

The basis of monogenic inheritance is the first and second laws of Mendel. Polygenic is based on the third law. This implies the inheritance of several genes, most often non-allelic.

Non-traditional inheritance does not obey the laws of heredity and is carried out according to its own rules that nobody knows.

Monogenic inheritance of

This kind of inheritance of traits in humans is subject to Mendeleev's laws. Considering the fact that there are two alleles of each gene in the genotype, the interaction between the female and male genomes is considered separately for each pair.

Based on this, the following types of inheritance are distinguished:

1. Autosomal dominant.
2. Autosomal recessive.
3. The X-linked dominant inheritance.
4. X-linked recessive.
5. Hollandic inheritance.

Each type of inheritance has its own characteristics and attributes.

Signs of autosomal dominant inheritance

The type of inheritance autosomal dominant is the inheritance of predominant traits that are located in the autosomes. The phenotypic manifestations of these may be very different. In some, the sign may be barely noticeable, but its manifestation may be too intense.

The type of inheritance autosomal dominant has the following features:

1. The symptom of pain is manifested in every generation.
2. The number of patients and healthy is approximately the same, their ratio is 1: 1.
3. If children of sick parents are born healthy, then their children will be healthy.
4. The disease affects both boys and girls alike.
5. The disease is equally transmitted from men and women.
6. The stronger the impact on reproductive functions, the greater the likelihood of different mutations.
7. If both parents are ill, the child, being born homozygous for this symptom, is more ill than in the heterozygote.

All these signs are realized only under condition of full domination. In this case only the presence of one dominant gene will be sufficient for the manifestation of the trait. The type of inheritance autosomal dominant can be observed in humans when inheriting freckles, curly hair, brown eyes and many others.

Autosomal dominant signs of

Most of the individuals who carry the autosomal dominant pathological feature are heterozygous for it. Numerous studies confirm that homozygotes with a dominant anomaly have more serious and severe manifestations compared with heterozygotes.

This type of inheritance in humans is characteristic not only of pathological signs, but some quite normal ones are inherited as well.

Among the normal characteristics with this type of inheritance can be noted:

1. Curly hair.
2. Dark eyes.
3. Straight nose.
4. Puncture on the bridge of the nose.
5. Baldness at an early age in men.
6. Mimicking.
7. Ability to fold a language with a pipe.
8. A dimple on the chin.

Among the anomalies that have an autosomal dominant inheritance type, the following are most known:

1. Multiple fingerprints, maybe on hands or feet.
2. The fusion of the phalanges of the fingers.
3. Brachydactyly.
4. Marfan syndrome.
5. Nearsightedness.

If dominance is incomplete, then the manifestation of the trait can not be observed in every generation.

Autosomal recessive type of inheritance

A symptom with this type of inheritance can only appear if a homozygote is formed in this pathology. Such diseases proceed more severely, because both alleles of one gene have a defect.

The likelihood of such signs increases with closely related marriages, so in many countries an alliance between relatives is prohibited.

The following are the main criteria for such inheritance:

1. If both parents are healthy, but are carriers of a pathological gene, the child will be sick.
2. The gender of the unborn child does not play any inheritance.
3. In one couples, the risk of having a second child with the same pathology is 25%.
4. If you look at the pedigree, you can see the horizontal distribution of patients.
5. If both parents are sick, then all children will be born with the same pathology.
6. If one parent is sick and the second is a carrier of such a gene, then the probability of producing a sick child is 50%.

Many types of diseases related to metabolism are inherited in this type.

Type of inheritance linked to the X-chromosome

This inheritance can be either dominant or recessive. The signs of dominant inheritance include the following:

1. Both sexes can be affected, but women are 2 times more likely.
2. If the father is sick, then he can pass the sick gene only to his daughters, because the sons from him receive the U-chromosome.
3. A sick mother is equally likely to award children of both sexes with this disease.
4. Severe disease in men, because they do not have a second X chromosome.

If there is a recessive gene in the X chromosome, the inheritance has the following symptoms:

1. A sick child can also be born in phenotypically healthy parents.
2. Men are most often sick, and women are carriers of a sick gene.
3. If the father is sick, then the health of the sons can not be worried, from him they can not get a defective gene.
4. The probability of the birth of a sick child in a female carrier is 25%, in the case of boys, it rises to 50%.

So are inherited such diseases as hemophilia, color blindness, muscular dystrophy, Callman's syndrome and some others.

Autosomal dominant diseases

For the manifestation of such diseases it is sufficient to have one defective gene if it is dominant. Autosomal dominant diseases have some characteristics:

1. At present, there are about 4000 thousand such diseases.
2. Both individuals are affected equally.
3. Phenotypic demorphism is clearly manifested.
4. If there is a mutation of the dominant gene in gametes, then it certainly will manifest itself in the first generation. It has already been proved that men with age are at increased risk of getting such mutations, and, therefore, they can award their children with such diseases.
5. Disease often manifests itself in all generations.

Inheritance of a defective gene of an autosomal dominant disease is not related to the child's sex and the degree of development of the disease in the parent.

Autosomal dominant diseases include:

1. Marfan syndrome.
2. Huntington's disease.
3. Neurofibromatosis.
4. Tuberous sclerosis.
5. Polycystic kidney and many others.

All these diseases can manifest themselves in varying degrees in different patients.

Marfan Syndrome

This disease is characterized by affection of the connective tissue and, consequently, its functioning. Disproportionately long limbs with thin fingers give reason to assume Marfan syndrome. The type of inheritance of this disease is autosomal dominant.

You can list the following signs of this syndrome:

1. Slim figure.
2. Long spider fingers.
3. Defects of the cardiovascular system.
4. The appearance of stretch marks on the skin for no apparent reason.
5. Some patients note pain in the muscles and bones.
6. Early development of osteoarthritis.
7. Curvature of the spine.
8. Too flexible joints.
9. Possible speech impairment.
10. Visual impairment.

It is possible to call symptoms of this disease for a long time, but most of them are associated with the bone system. The final diagnosis will be made after all the examinations have been completed, and the characteristic features are found in at least three organ systems.

It can be noted that some of the signs of the disease do not appear in childhood, but become apparent somewhat later.

Even now, when the level of medicine is high enough, it is impossible to completely cure Marfan's syndrome. Using modern drugs and treatment technologies, it is possible to prolong the life of patients with such a deviation and improve its quality.

The most important aspect in the treatment is the prevention of the development of aortic aneurysms. Regular consultations of the cardiologist are obligatory. In emergency cases, surgery for aortic transplantation is indicated.

Huntington's chorea

This disease also has an autosomal dominant inheritance type. It begins to appear from the age of 35-50 years. This is due to the progressive death of neurons. Clinically, you can identify the following symptoms:

1. Disordered movements in combination with a decreased tone.
2. Asocial behavior.
3. Apathy and irritability.
4. Manifestation of a schizophrenic type.
5. Mood swings.

Treatment is aimed only at eliminating or reducing symptoms. Use tranquilizers, neuroleptics. No treatment can stop the development of the disease, therefore approximately 15-17 years after the onset of the first symptoms death occurs.

Polygenetic inheritance of

Many signs and diseases have an autosomal dominant inheritance type. What is it is already clear, but in most cases everything is not so simple. Very often there is an inheritance of not one, but several genes. They are manifested in specific environmental conditions.

A distinctive feature of this inheritance is the ability to enhance the individual action of each gene. The main features of such inheritance include the following:

1. The more severe the disease, the greater the risk of developing this disease in relatives.
2. Many multifactorial signs hit a certain gender.
3. The more relatives have such a sign, the higher the risk of the appearance of this disease in future offspring.

All considered types of inheritance refer to classical variants, but, unfortunately, very many signs and diseases can not be explained, because they refer to non-traditional inheritance.

When planning the birth of a baby, do not neglect a visit to a genetic consultation. A competent specialist will help you understand your pedigree and assess the risk of a child with deviations.