The original classification of the ABO system was made by Karl Landsteiner in 1900. The ABO system consists of four blood groups or phenotypes: A, B, AB and O. The two antigens, A and B are responsible for these four groups. If A antigen is present on the red cell, the individual is said to belong to group A. Those having B antigen are group B persons. Group AB individuals have both A and B antigens while group O persons have neither A and B antigens on their red cells.
The allelic genes A, B, and O, can be inherited in the ABO system. The following combination of allelic is possible: AA, AO, AB, BB, BO, and OO, resulting in AA, AB, BB, and O group individuals respectively. This is so because A and B genes are dominant and O gene is recessive
LAWS OF INHERITANCE OF ABO GROUPS
According to Bernstein’s theory, two laws of inheritance have been proved.
1 – It is not possible that an offering can possess antigen A, B or both unless it is inherited from one or both parents.
2 – A parent of blood group AB cannot produce an offspring of group O. Similarly, a parent of blood group O cannot produce AB offspring. The reason for this law is that group AB is heterozygous, and therefore A and B genes must come from two parents.
For antibodies in the serum, according to Landsteiner’s rule, corresponding antibodies cannot co- exist in the same person blood for example, persons who are blood group A cannot have antibodies to antigen A (anti A) in their blood and group B persons cannot have anti – B in their blood for ABO system. Hence a person of group A has anti B in serum, while a person of group B will have anti A and a person of group O will have both anti A & anti B in the serum and blood group AB will have neither antibody in their serum (blood).
Rhesus Factor is an antigen that exists on the surface of red blood cells in most people (about 85% of humans). It is also referred to as Rh Factor. People who have the Rh have “positive” (+) blood types, such as A+, O+ or B+ are said to be rhesus Factor positive, while those who have the Rh “negative” (-) blood types, such as A–, O– or AB– are said to be rhesus factor negative . The “+” and “-” in front of the blood group is the Rhesus factor. Generally, we have A+, A–, B+, B–, AB+, AB–, O+ and O–. Rhesus factor is genetic in nature. It is inherited from the parents, emphatically the father.
How does Rhesus Factor cause miscarriage?
If a Rh– woman is impregnated by a man with Rh–, there wouldn’t be any problem. However, if a Rh– woman is impregnated by a man with Rh+, there would be a problem if the baby inherits Rh+ from the father.
We have here what is medically called Rhesus Factor Incompatibility. The baby would obviously be Rh+. During child birth, once the baby’s Rh+ comes in contact with the woman Rh- during delivery, the antibodies are immediately activated by the woman’s body’s immune system.
The activated antibodies would see the new Rh+ as foreign body or a threat and consequently they would be at alert to attack and get rid of the foreign body. Unfortunately as such, after this particular child birth, the woman would keep having miscarriages because the activated antibodies would see subsequent Rh+ pregnancies as foreign bodies and would keep fighting and taking them off.
Women with Rh activated antibodies are said to be Rh sensitized and once these antibodies are activated , they can never be deactivated until the woman dies. Rh induced antibodies are activated in a Rh- woman by child birth, abortion, miscarriage and ectopic pregnancy.
If a Rh– woman commits an abortion for a Rh+ man and the antibodies are activated in her system, the woman might end up childless throughout her life except if she later marries another man with with the same Rh–. The possibility of a Rh– woman finding a Rh– man is slim as about 85% of human beings are Rh+. This is a warning to our young girls who commits abortions all in the name of boyfriend-girlfriend relationships.
If you’re a woman with Rh– and your fiance is Rh+, and you haven’t committed abortion for him and you don’t want to leave him, then, you need to take note of the following:
In order to prevent the activation of the antibodies, doctors would give women in this category an injection called Rhogam during and after pregnancy to prevent spontaneous abortion due to Rhesus factor incompatibility.
The injection is normally administered 28 weeks into pregnancy, 72 hours after delivery, after ectopic pregnancy, miscarriage or abortion. If the injection is not administered and the antibodies are activated, they would never be deactivated again!
In many African cultures up till today, women who are so unfortunate to find themselves having serial spontaneous abortions due to Rhesus factor incompatibility are considered witches by some of their people. Some of the women would accuse their in-laws of being behind their predicament.
So, if you’re a woman with Rh–, you need to be very careful. It might be difficult for you to get a husband with a Rh– because about 85% of human beings are Rh+. So, in order not to find yourself in the aforementioned problem, put all that have been said at the back of your mind and go for genetic counselling. If you have a daughter or a sister with Rh–, counsel them on Rhesus Factor Incompatibility and the dangers lying therein.
It should also be noted that a Rh– person(man or woman) cannot receive blood donation from a Rh+ person even if they have the same blood group. The consequence of such blood transfusion is fatal. It would lead to death as the blood would clot. This is due to the incompatibility in their Rhesus factor.
Ideally, an Rh-negative woman is supposed to marry an Rh-negative man. With this type of marriage all the offspring will be Rh-negative and there will be no foreign agent for sensitization of the mother to produce anti-D against subsequent pregnancies or babies. The challenge here however, is that Rh-negative individuals are very few in the society to make this type of marriage possible. As a result, majority of the Rh-negative women will end up marrying Rh-positive men. Hence the risk of haemolytic reaction occurring.
Anti D is now administered to every RhD-negative mother giving birth to an RhD-positive child, provided she is not already immunized to the D antigen by previous pregnancy or blood transfusion. It is important that the dose of anti-D given should be adequate to clear all the foetal red cells from the maternal circulation. and the appropriate dose of anti D should be given as soon as possible after delivery and not later than 72 hours post partum. In case of abortion, it is assumed that the foetus is Rh (D) positive (unless the father is also Rh negative) and anti- D should also be given.
Any event during pregnancy which might lead to a transplacental bleed (e.g. trauma, obstetric manipulation, amniocentesis, should be covered by an appropriate injection of anti-D. This treatment helps to protect mother against future pregnancies from potential implication related to Rh-incompatibilities.
In conclusion, it is important for couples with Rh group differences to seek guidance from health care providers before planning for pregnancy especially, when the woman is Rh negative and the man Rh positive. Regular prenatal care and monitoring are essential to ensure the health and wellbeing of both mother and the baby.
Know your Rhesus factor today! Kindly share this knowledge with your friends and community.
REFERENCES:
ASIDE KNOWING YOUR GENOTYPE before MARRIAGE, THERE'S NEED FOR ONE TO KNOW HER RHESUS FACTOR! RHESUS FACTOR INCOMPATIBILITY IS A LEADING CAUSE OF MISCARRIAGE!
Rhesus Factor is an antigen that exists on the surface of red blood cells in most people (about 85% of humans). It is… pic.twitter.com/qaXhQEi4Gp
