At the beginning of the last century, scientists proved the existence of different blood groups. This is a whole system of recruitment of genes received from parents. Based on the results of numerous studies, mom and dad pass on the blood type to the child. What can it be, how is it inherited? In this article we will try to answer these questions.
A bit of history
During the experiments, the scientist Karl Landsteiner revealed that during the mixing of the blood of some people with the blood taken from others, gluing of red bodies (red blood cells) may occur, due to which clots form. After that, the scientist began a detailed study of red blood cells, as a result of which he found substances of a special type. He divided them into A and B categories. Karl also discovered the third category, which describes cells that do not contain special elements.
After some time, A. von Decastello and A. Sturli found red blood cells, which contained elements A and B at once.
As a result of the work of these scientists, an ABO system was created that divides blood into groups. This system is familiar to us in the following form:
- I (O). This is the first group, which is characterized by the absence of antigens A and B.
- II (A). Blood with antigen A.
- III (B). Blood with B. antigen.
- IV (AB). This group is characterized by the presence of two types of antigens at once - both A and B.
After this discovery, doctors were able to rule out transfusion losses that once occurred due to the incompatibility of donor blood and the recipient. Although there have been cases of successful transfusion.
The ABO system has allowed a complete change of opinion about the nature of blood. In the future, genetics proved the identity of the principles of inheritance of a blood type by a child from parents, as well as obtaining other signs. In the second half of the twentieth century, Mendel discovered the laws of heredity, based on the results of experiments on peas.
Mendel's laws
Scientists have proved the laws that determine which blood type a child will inherit from parents:
- Dad and mother with the first group can only have children with the first group. This is due to the fact that they do not have antigens A and B.
- If the parents have the first and second groups, then the children will have the same groups. The same will happen if parents have the first and third.
- For parents with a fourth blood group, the child will have any blood except the first group.
- There are people who have antigens A and B, but they do not appear. This variety is most often found among Indians and is called the "Bombay phenomenon."
Rhesus factor
If both parents have positive Rhesus in the family and the baby is negative, then distrust of the spouse may occur, although it is formed from scratch.
The Rh factor is a unique, special protein that is located on the surface of red blood cells. Approximately 85 percent of the world's population has this protein, while the rest do not. In the first case, a positive (+) Rh factor is diagnosed, and in the second, a negative (-) one. These same factors are designated as Rh. To conduct research, usually take a pair of genes.
Like a blood group, the child inherits the Rh factor, but a slightly different principle applies here.
Positive Rhesus is usually indicated by Latin DD or Dd. Most often it is dominant, and negative rhesus indicate dd and it is recessive. If spouses have heterozygous Rhesus Dd, then in 75% of children they will have a positive (+) Rhesus, and the rest will have a negative (-).
If the parents are carriers of Dd and Dd, then they can have children in different genotypes: DD, Dd, dd.
The table will help to understand the principle of inheritance:
ABO blood inheritance
And what kind of blood group will the child have if the parents have the first and second group? Similar questions are often asked by future parents. The answer to it and other questions in the table:
Heredity
In addition to the blood type, the child shows other signs from the parents. For many centuries, people have fantasized what a child can be, but heredity takes its toll.
Today, ultrasound allows you to accurately determine the sex of the future baby, to see developmental abnormalities. Genetics allows you to determine what will be the color of the hair, eyes, whether the child will have a musical ear. These signs are dominant and recessive. To find out what is the probability of inheritance, you should turn to the laws of Mendel.
The dominant properties include brown eyes, curly hair, the ability to turn the tongue into a tube. If one of the parents has these symptoms, then the child is likely to receive them.
Less joyful is the fact that if parents turn gray early, go bald, then this will be passed on to children, since this is also a dominant sign. Also, children will most likely have a large gap between the front teeth, myopia.
But blue eyes, straight hair, fair skin - all these are recessive signs that are more difficult to inherit.
Sex determination during pregnancy
For a long time, women were accused of the absence of heirs in families. But are women to blame for this? Genetic scientists have found that eggs and sperm have 23 chromosomes, 22 of which coincide with the sex cells of the spouse, and the latter does not match - this is a female pair - XX, male - XY.
The gender of the unborn baby depends on the set of papal chromosomes, that is, on those 23 chromosomes that are contained in sperm.
ABO compatibility
At the stage of pregnancy planning, when partners suspect immunological infertility, they check the compatibility of blood groups for conception of a child.
Incompatibility occurs only when agglutinogens are found in the blood of one of the spouses, and the other agglutinins are found in the other, for example, A and a, B and b. In such cases, gluing of the red blood cells of the fetus occurs.
In rare cases, a third blood group may begin to form in children, which is incompatible with maternal ABO. In such cases, an immunological conflict occurs, i.e. a miscarriage occurs in the early stages or a child is born with a hemolytic disease.
Rh compatible
The blood type of the father, mother, child can rarely be incompatible, most often there is a Rhesus conflict. This phenomenon occurs when a woman has a negative Rhesus and becomes pregnant with a child with a positive Rhesus Rh (+).
In this situation, fetal proteins enter the mother through the general bloodstream, where they are met by the immune system. She perceives these proteins as foreign objects. At this point, the female body begins to produce antibodies that cause the death of red blood cells in the fetus.
If a woman has this first pregnancy, then serious changes do not occur, since the immune system responds slowly to the fetus in a positive Rh factor. And does not have time to develop the right amount of antibodies. With repeated pregnancy with a baby with positive Rh immunity begins to kill red blood cells, but if the fetus has Rh negative, then the baby will develop normally, without threats.
Incompatibility of partners
Before deciding to have a baby, you should be trained. It includes not only the cure of all current diseases, but also a compatibility test. In some cases, you have to turn to geneticists. Typically, such a need arises in cases where the mother’s and the child’s blood types conflict.
Usually, with ABO incompatibility, spouses have to look for alternative options for conception or to adopt a child.
If the partners of the Rh factor are incompatible, you should not worry during the first pregnancy, as the female body will not “attack” the fetus. After childbirth, the first child must determine the blood group and Rh factor. If the first pregnancy ends with an abortion, miscarriage, then the woman is injected with an anti-Rhesus immunoglobulin to prevent the Rh conflict of the mother and the fetus.
Knowing whether the blood type of the child and mother can be incompatible, which parent groups and Rh factors are suitable for each other, you can safely plan a pregnancy. In the event that there is a possibility of incompatibility, then you can try to fix this by applying the method recommended by your doctor.