At birth, the baby gets from mom and dad a double set of chromosomes, in which the encoded information about the features of red blood cells, which determines the blood group type.
But often parents and children do not match the parameters of red blood cells. It helps to find out what may be blood in the child from the parent table.
Mendel's Law
Transmission of hereditary characteristics does not happen by accident, and obey the laws of genetics. The basis for determining the blood type of the child by parents is the law of Mendel, which opened in 1836, and the table Landsteiner, which appeared in 1901
Immunologist Landsteiner, who worked in the last century, discovered 3 types of red blood cells (RBCs). He found that the surface of red cells 2 categories carries special proteins, which gave the name of the scientist antigen A, antigen B, and red blood cell antigens are absent in the third form.
Since Category 3 erythrocytes was discovered, and later found a fourth, where red blood cells contain both antigens.
Mendel's laws to help understand how hereditary characteristics are passed on to offspring. In relation to erythrocyte antigens acts dominate the law, or the first law.
According to the law, the offspring show signs of one of the spouses. Exceptions are erythrocytes 4 categories, bearing on the surface of protein A and protein B.
This case is not contrary to Mendel's law, it belongs to the mixed dominance when inherited attributes are shown simultaneously.
Studies Mendel, Landsteiner and other scientists have established the basic principles of inheritance:
- Chromosome set is inherited.
- The genotype of the progeny is composed of two genes obtained from the mothers and fathers.
Appearance encoded antigens:
- dominant genes - responsible for the synthesis of antigen A, antigen B;
- recessive gene - is denoted as 0, which means the absence of antigens A, B.
The red blood cell chromosomal genes simultaneously present from mum and dad, but appear only dominant traits.
This means that with a combination of A0 or B0 group of inherited blood protein body protein A or B.
If the progeny inherits dominant gene A and B, formed by the combination of the AB, and mixed there (fourth) category erythrocytes.
By combinations of antigens distinguished group affiliation:
- first - 00;
- second - A0 / AA;
- third - B0 / BB;
- fourth - AB.
When the parents are inherited recessive genes, it appears genotype 00, which is typical of the first group. In this case, the membrane of red blood cells can not be found proteins A and B.
In group 2 parental genotype may be two options. When transferring offspring genotypes:
- A0 - transmitted variants A and 0;
- AA - will be transferred only A.
When the parent is inherited genotype 3 type:
- B0 - variants B and 0;
- BB - only B.
From spouses with genotype A0 and B0 offspring can get not only the mother's or father's red blood cells, but also options such as:
- 00 - the first group;
- AB - fourth.
A variety of options depends on the parental genotypes. Mixed type A0 or B0 genotype 4 given combination.
But if the parental genotypes are represented by a combination of AA and BB, the formed mixed genotype AB. The heir is only 4 group.
In Mendel's Law, there are exceptions. It is not always possible to accurately calculate the child's blood group, guided only by this rule.
Inheritance Violation occurs in exceptional cases, such as when the phenomenon of Bombay, when a mother 00 and father with A0 born offspring with B0.
If the parents the same blood group
Offspring gets genes from the mother and father, but they can be represented by different genotypes. Thus, if both partners group 3, it is possible that children are born with 1 and 3, blood type, as descendants inherited B0 / BB or 00 genotypes.
With 100% probability to calculate group membership hematopoietic system of the baby can only be, if He was born to mothers and fathers to one (first) type of erythrocytes, on which surface no dominant antigens.
But even in this case erythrocytes specifications may vary. Parents with one group may be different other signs.
If both parents have type 2 blood, which corresponds to A0 / AA, then the children will:
- 25% chance first category erythrocytes;
- in 75% of cases - the second.
In a third category of the blood of the mother and father, when red blood cells are present 0 and B, the progeny inherit:
- 25% of the cases - the first;
- 75% - the third.
Harder identifiable group of blood in children of parents, if the genotype AB pairs corresponds to a mixed type.
If mom and dad have genotype AB, then the pair may receive a child with 3, 2 or 4 group. With 50% probability of offspring genotype coincides with the parent. On the possibility of 2 and 3 groups accounted for 25% of all potential cases.
The surface of the red blood cells carries not only the proteins that determine the group affiliation of red blood cells. On the surfaces of erythrocyte proteins have no or Rhesus (Rh).
If the parents Rh is present, the blood is Rh-positive, in the absence thereof - Rh-negative. When the red blood cells from mum and dad carry the Rh membrane, then the offspring will be Rh-positive.
When Rh-negative blood from mum and dad inherited the same type of red blood cells.
Mother and father with the second group will give the child a positive A0, 00 and Rh +.
If the parents have different blood groups
Blood type children zaisimosti of genotypes mom and dad can be the same or different from the parent. The couple will be born offspring of my mother's or father's group, if the parents first and second or first and third.
The mother with one group (00) and from father 2 (AA, A0) the child may be born with a combination of antigens 0 and A.
The pair 1 and 2 have B antigen groups. This means that neither the third nor the fourth group of offspring of mother 1 (00) and father with type 2 can not be.
Only 2 options is a child born to the couple with the first and third group.
The appearance of the offspring of three variants of genotypes may have a pair of genotypes:
- AA or A0 and AB - the first + the fourth group;
- B0 or with BB AB - third + fourth type.
But the calculated category does not always coincide with the actual type of the blood of the newborn.
baby's blood group can vary and from my father and from my mother's version. Such children may be born, if the spouses have 2 and 3 groups.
The combination gives the most options. The second and third groups, the couple gives the offspring of one of the four categories of red blood cells.
The couple with 2 or 3 groups with a high probability of a baby 4, or 1 of blood type.
It does not violate the laws of inheritance appearance of parents with antigens AA / A0 and B0 / BB children with antigens 00 and AB. This is a case where it may be in the child's blood group different from their parents.
Table options
Possible blood groups in the offspring can be determined by the inheritance of the table, which presents possible options. With the help of the table is easy to calculate what the group inherited by the offspring, if one pair of blood group affiliation:
| Parents | Group affiliation offspring blood (%) | |||
| 1 | 2 | 3 | 4 | |
| 1 | 100 | — | — | — |
| 2 | 25 | 75 | — | — |
| 3 | 25 | — | 75 | — |
| 4 | — | 25 | 25 | 50 |
Full match in the group does not mean that the blood of parents and children is identical. blood types may vary on the Rh factor.
If we consider a difference of antigen by Rh factor, the number of options increases. More types can be passed to children of couples with different groups.
Embodiments inheritance from spouses with different groups are indicated in the table. It will help calculate what the genotype of the child inherits:
| Father + mother | Blood group of children (%) | |||
| 1 | 2 | 3 | 4 | |
| 1+2 | 50 | 50 | — | — |
| 1+3 | 50 | — | 50 | — |
| 1+4 | — | 50 | 50 | — |
| 2+4 | — | 50 | 25 | 25 |
| 3+4 | 25 | — | 50 | 25 |
| 2+3 | 25 | 25 | 25 | 25 |
To know what has to be the kind of blood in the offspring, it is necessary to provide for the possible incompatibility of the mother's blood and the developing fetus during pregnancy.
Conflict of AB0 antigen system noted much less frequently than the mother and fetus incompatibility of Rh factor. But the mother's body to produce antibodies to the fetus, causing its destruction of red blood cells if the mother genotype 00, and the fetus - whatever.
Preliminary calculation does not help to change the group membership of the offspring of red blood cells. But knowing the genotypes of erythrocyte spouses easily calculate all the options from the heirs.
