The ABO system and the inheritance of the blood group in humans

About what the blood groups are, you should know!

Antigens of the blood system

Antigenic structure of the human bodyis incredibly complex. Only in blood, modern science has discovered about 500 antigens combined into 40 antigenic systems: MNSs, AB0, Kell, Duffi, Luteran, Lewis, and others.

Each of the antigens of these systems isgenetically encoded and inherited by allelic genes. For simplicity, they are all subdivided into plasma and cellular. For cellular hematology and transfusiology, cellular antigens (erythro-, thrombotic- and leukocyte) are of great importance, since they have immunogenicity (the ability to induce an immune response), and therefore, when transfused with blood-cell antigens incompatible, there is a risk of developing hematogenous shock or DIC-syndrome with lethal outcome. Blood antigens consist of two main parts: the antigenic determinant determining immunogenicity, and the hapten, "weighting" the antigen and determining serological activity.

The first part is highly specific forof each antigen, and therefore distinguishes them from each other. So, in the system AB0 antigen 0 differs fucose, antigen A-N-ftsetilglyukozamin, and antigen B-galactose. These antibodies are attached to these determinants in the development of the immune response. These antigens are taken into account during blood transfusion, and also when the possible inheritance of the blood group is calculated.

AB0 system and its inheritance

As early as 1901, human blood was detectedsubstances capable of gluing together erythrocytes among themselves, called agglutinins (plasma agglutination factors - α and β) and agglutinogens (erythrocyte adhesion factors - A and B).

According to this system, the scientists J. Iański and K. Landsteiner divided all people into 4 groups, they also calculated the inheritance of blood groups in humans. So, the I blood group has people whose blood contains no agglutinogens, but the plasma contains both agglutinins. Their blood is designated as αβ or 0. People with the II blood group have agglutinogen A and agglutinin β (Aβ or A0); people with group III, on the other hand, have agglutinogen B and agglutinin α (Bα or B0), and the IV group of blood differs in the presence of erythrocytes of both agglutinogens A and B (AB), with no agglutinins. They are determined by a simple laboratory method using special standard sera. Since both agglutinogen are dominant, the inheritance of one of the antigens, i. E. inheritance of the blood group, proceeds in the same way. The blood group of the unborn child can always be assumed with a probability of 100, 50 or 25% with different combinations of blood groups of the parents. Thus, knowing their antigens, the inheritance of blood groups of children can be traced through the following table.

Blood type	Father
Mothers	I (00)	II (A0)	II (AA)	III (B0)	III (BB)	IV (AB)
I (00)	00 - 100%	00 to 50% A0 = 50%	A0 = 100%	00 to 50% B0 - 50%	B0 - 100%	A0 = 50% B0 - 50%
II (A0)	00 to 50% A0 = 50%	00 - 25% A0 = 50% AA - 25%	AA - 50% A0 = 50%	00 - 25% A0 = 25% B0 - 25% AB - 25%	AB - 50% B0 - 50%	AA - 25% A0 = 25% B0 - 25% AB - 25%
II (AA)	A0 = 100%	AA - 50% A0 = 50%	AA - 100%	AB - 50% A0 = 50%	AB - 100%	AA - 50% AB - 50%
III (B0)	00 to 50% B0 - 50%	00 - 25% A0 = 25% B0 - 25% AB - 25%	AB - 50% A0 = 50%	00 - 25% B0 - 50% BB - 25%	BB - 50% B0 - 50%	A0 = 25% B0 - 25% BB - 25% AB - 25%
III (BB)	B0 - 100%	AB - 50% B0 - 50%	AB - 100%	BB - 50% B0 - 50%	BB - 100%	AB - 50% BB - 50%
IV (AB)	A0 = 50% B0 - 50%	AA - 25% A0 = 25% B0 - 25% AB - 25%	AA - 50% AB - 50%	A0 = 25% B0 - 25% BB - 25% AB - 25%	AB - 50% BB - 50%	AA - 25% BB - 25% AB - 50%

Equally important is knowledge of the Rh factor, sinceit is also important for the compatibility of blood groups during transfusion. Thus, Rh-positive blood (Rh +) is possible to transfuse a patient with Rh-negative (Rh-) blood only once for the life and in extreme cases, since the first transfusion will develop Rh antibodies, which are activated at a second transfusion (and the recipient at risk to die from blood transfusion shock). The same applies and rhesus conflict with the conception of the fetus with Rh-positive blood from Rh + Rh- mother and father, so it is important to calculate the inheritance of the blood group of the child.

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