How is the Rh factor inherited, and what determines the degree of predominance of the minus or plus next to the letter R? It is worth immediately paying attention that the field of formation depends on DNA, blood type, compatibility, allele and genotype. If we turn to biology, then in the crossing section we consider such an interesting detail as the dominant and recessive trait of heredity. It also determines what blood will flow in the circulatory system of the descendant.
Types of blood of people - property of hereditary heritage
There are four main types of blood: A, AB, B, and O. AB positive is considered a universal recipient, and O negative is considered a universal donor. To understand how the Rh factor is inherited, you can present data in a table or draw by hand. Your ABO blood type is based on the presence or absence of A and B antigens on your red blood cells.
- Type A blood has only antigen A.
- Type B blood has only antigen B.
- Blood type AB has both antigens A and B.
- Blood type O has neither antigen A nor B.
By the time you are six months old, you are naturally developing antibodies against antigens that your red blood cells lack. For example, a person with type A blood will have anti-B antibodies, and a person with B type blood will have antibodies against A. If you have type A blood, you cannot get B-blood because your bodyās antibodies will fight B blood antigens. It is imperative that all patients have all types of blood. But how does a person inherit the Rhesus factor, and why does someone have āgoodā heredity and someone ābadā heredity?
Blood Inheritance - Three-Dimensional ABO Type
Each person has an ABO blood type (A, B, AB or O) and a Rh factor (positive or negative). Just like the color of hair or eyes, our blood type is inherited from our parents. Each biological parent donates one of two ABO genes to their child. Genes A and B are dominant, and the O gene is recessive. For example, if the O gene is conjugated to the A gene, the blood type will be A. For example, a parent with O-blood with two O-genes and a parent with A-blood with two A-genes will have a child with type A blood with one A gene and one O-gene. Thus, the pattern of how the negative Rh factor is inherited is visible.
The Rh factor is simply a protein that is found on the coating of red blood cells. If your red blood cells have this protein, you are Rh-positive. If the blood cells do not have this protein, you have a negative result. Just as everyone inherits ABO genes, a person inherits one Rh factor gene from each parent. The Rh-positive gene is dominant when it is conjugated to the Rh-negative gene.
How is the Rhesus factor of the blood of an unborn child inherited?
It was once believed that blood types stay with people for life. And in almost every case, they still remain with the person to death. But there is one case where the type of blood has really changed. Liver transplantation, apparently, has a chance to change the type of human blood, and if there are preconditions for surgery, you need to know in advance what to do next in case of donation of blood and antibodies - after all, a biological parent can not even be a donor now? It is true that another question arises from this: how is the Rh factor of the blood inherited if it has been changed?
Once there was a simple time in the history of mankind, when everyone had only one type of blood, and it was negative. This explains the very presence of the gene, otherwise, where does it come from? Life continued its usual century of evolution, and suddenly small particles of protein agglutination were found on the surface of beautiful, smooth red blood cells. This was what is now known as the Rh factor, which turns O-negative blood into positive O. Then there were other small clusters of protein that separated Rh positive blood and negative Rh into types A and B.
For the vast majority of historians and scientists, only the Rh factor caused particular concern. The information reading system saw a pregnant woman with Rh-negative blood as an external body attacking her own descendant. This is such a natural selection by nature, which today presented a little, no less than 85% of people with Rh-positive data.
The evolution of discovery - the birth of an answer raises questions
Meanwhile, types A and B were only beginning to bother humanity by the time the blood transfusions and organ transplants took place. Again, the immune system attacked strangely soaked blood cells and caused medical problems. Type O patients, approximately forty-five percent of the population, could donate their blood and organs, but could not receive anything suitable in case of emergency care. The resonance factor of the blood depended on what type of medical procedure was performed.
So the world began to worry about these little drops of blood. Since it was genetic, the type of blood remained with the person for life, and there was no way to get around the options. Many wondered how the blood group and the Rh factor are inherited, if it is not an acquired indicator.
Technically, it depends on what people are divided by type of blood. Genes do not change. However, scientists noticed that after bone marrow transplantation, āregenerated patientsā sometimes slowly developed blood types of the donor. Bone marrow was used to create one type of blood, but slowly filled people with cells that did not match their genotype. It made sense to establish the fact of organ rejection.
What antigens consist of: the process of formation and change of the Rh factor
Blood antigens are either sugars or proteins that are attached to the erythrocyte membrane. ABO antigens are the most clinically important antigens because they are immunogenic. Since erythrocyte antigens are inherited traits, they usually do not change throughout a personās life. Some patients found themselves in situations where blood group antigens were suppressed during their leukemic phase, and antigens were re-expressed when patients reached remission.
RBC antigens (RBCs) are inherited traits. And their expression is constantly throughout the life of a person. Due to hematologic malignant neoplasms, a change in RBC antigen has sometimes been observed. These modifications of blood group antigens usually return to normal after remission. In the case of acute myeloid leukemia (AML), patients had a change in ABO antigen during the acute leukemia phase and re-expression of their parent ABO antigen after remission. It was noted:
- Loss or decrease in the expression of RBC antigens was in both solid and hematological malignancies. Blood type antigen ABO is the most frequently modified blood type antigen (1-4). For hematopoietic diseases, the loss of expression manifests itself mainly from a mutation that affects the production of antigen in stem cells.
- A complete or partial loss of antigen expression is observed among PBC precursors arising from this affected stem cell, while erythrocytes arising from unaffected stem cells usually express normal RBC antigens.
- Loss or attenuation of ABO antigens is usually detected as a mismatch in direct and reverse patient typing. ABO antigens are the most frequently modified blood type antigens, as they are regularly tested for all patients before transfusion.
Thus, regardless of how the Rh factor of the blood is inherited from the parents, it can change, like the blood itself, during the illness.
The formation of new blood enzymes
A, B and H antigens are formed from the same precursor substance. Obtaining ABO antigens depends on the functioning of two glycosyltransferases. A negative Rh factor is inherited as an autosomal recessive one, and indicators such as:
- The first enzyme, H-transferase, adds L-fucose to terminal galactose precursor.
- Substance H is then exposed to A or B transferases that add N-acetyl galactosamine or galactose, respectively.
- There are two possible mechanisms for attenuation of ABO antigens in hematopoietic diseases.
The first mechanism is the inactivation of A / B transferases, and the second is the inactivation of H-transferase. Thus, any loss of ABO antigens should result in a search for underlying hematopoietic malignancy. Knowing in advance how the Rh factor is inherited by the child, significant errors can be avoided during any medical interventions. Variations of ABO antigens may also reflect malignancy status. After remission, the initial blood group returns, and with relapse, blood group antigens are suppressed. It turns out that after the disease, when the blood is restored, the disease will either āsurviveā the return to the true model of the body, or the relapse reaction will be launched.
What is rhesus and why is it needed in biochemical science?
It is known that a child with Rh-negative blood does not have a Rh factor, a protein located on the surface of red blood cells. People with this protein have Rh-positive blood, while those who donāt have this have Rh-negative blood. But the presence of Rh-negative blood is not a pathology. Those people who have a Rhesus negative can have more protection against some congenital diseases. However, a woman with Rh-negative blood can experience potentially serious complications during pregnancy if she does not receive timely medical care before giving birth.
At the moment of adaptation of the fetus to "temporary housing" there is a rhesus conflict, but in the case when only the father has a negative indicator, there can be no threat of fetal rejection.
Is the Rh factor inherited, and what is the reason?
In order for a child to have Rh negative blood, he needed to inherit two Rh negative genes: one from his father and one from his mother. A couple can have a child who does not have a Rh factor only if they are both Rh-negative or both have the same recessive Rh-negative gene. People with any of the main types of blood - A, B, O or AB- can be born Rh-negative. This is a fairly common occurrence, and about 15% of the population of Russia has a negative genotype. Of these, 3% have no rhesus at all - their parents both had an Rh-indicator.
Health effects
A child who has Rh-negative blood will not suffer from health problems directly caused by the absence of a Rh factor. Having this type of blood is just a trait that looks like brown hair or freckles. Medicine indicates that those who have Rh-negative blood have higher resistance to deadly parasitic toxoplasma than Rh-positive people. Genetics theorize that Rh-negative blood can be an adaptation that has developed to protect against parasites and viruses, although more research is needed.
Possible dangers for children
The only danger associated with Rh-negative blood is Rh disease, which occurs when a woman with Rh-negative blood plans a baby who is Rh-positive because she inherited a dominant Rh-positive gene from her father. With a genetic disease of Rh, the mother develops antibodies that destroy the red blood cells of the baby, causing liver and spleen erosion, anemia and jaundice. In severe cases, the condition can lead to severe development of hepatitis, brain damage, deafness, seizures, or premature death. Rh disease does not develop if the mother is Rh-positive and her baby is Rh-negative.
Prevention: is it appropriate in genetics?
The key to preventing Rh disease is early detection of the āailmentā. Women who receive antenatal care in the early stages of pregnancy are tested for the Rh factor. If their blood is Rh negative, they may be given Rh immunoglobulin or Rhlg, a blood product that inhibits any antibodies. Their motherās body produces by destroying Rh-positive baby blood cells. Most Rh-negative women receive Rhlg injections at the 28th week of pregnancy, as well as after any case that may ādisconnectā the contact between her blood and the fetal blood, including amniocentesis or abdominal trauma. This is how a Rhesus factor of blood and a genetic predisposition to subsequent transmission of genetic information are inherited in humans.