What You Must Know
First things first, being assured of Genotype and Blood Group compatibility with your partner is one of the most important factors of long-term happiness in your marriage, it helps you raise healthy children, and saves you a lot of stress in the happy marriage you dream of with your partner.
What is GENOTYPE?
Your genotype is your complete heritable genetic identity; it is your unique genome that would be revealed by personal genome sequencing. However, the word genotype can also refer just to a particular gene or set of genes carried by an individual. For example, if you carry a mutation that is linked to diabetes, you may refer to your genotype just with respect to this mutation without consideration of all the other gene variants that your may carry.
This is different from your phenotype which is a description of your actual physical characteristics. This includes straightforward visible characteristics like your height and eye color, but also your overall health, your disease history, and even your behavior and general disposition. Do you gain weight easily? Are you anxious or calm? Do you like cats? These are all ways in which you present yourself to the world, and as such are considered phenotypes. However, not all phenotypes are a direct result of your genotype; chances are that your personal disposition to cats is the result of your life’s experience with pets rather than a mutation in a hypothetical cat fancier gene. This article however focuses on the genotype and blood group compatibility, so we keep it that way.
The genotypes in humans are AA, AS, AC, SS, SC, CC.
Now let’s explain what all the AAs and ACs mean.
According to an online publication by Laumsites Ywc – What you have in your blood are cells, the most predominant of which are called RED BLOOD CELLS (RBCs).
These cells contain within them HEMOGLOBIN, a substance without which the RBCs are invariably useless.
This hemoglobin itself is composed of 2 parts: a heme (don’t bother yourself, this basically is a complex Iron-protein complex) and globin (2 pairs of protein chains, this is the important part).
There are 2 alpha and 2 beta globin chains – the pair, and there is a normal way the chains are supposed to be structured.
The error happens when a protein substitution occurs in any one of these chains – but particularly in the globin chains (First of all, you have to understand that amino acids are the building blocks of proteins – so if amino acid ‘x’ is the normal, an abnormality occurs when instead of ‘x’ at a particular location along the chain, you have ‘y’.)
There are different types of Hemoglobin; among them are Hemoglobin A, Hemoglobin S and Hemoglobin C.
Hemoglobin C is very rare.
Everyone must have a pair of these hemoglobin in their blood, each inherited from both parents. The pairing might be in any of the following formations: AA, AS, AC, SC, SS OR CC.
People with the genotype AA are prone to malaria sickness at their early ages. Sickle cell arises when there is any blockage in the blood vessels which inhibits the flow of oxygen. When the red blood cell do not have the required oxygen, there will be changes in its original shape (disc shape) to a“Sickle-like” or “crescent-like shape”, Thus, the name “sickle cell”. Sickle cell patients experience severe pains in body parts that lack oxygen flow. Their bone marrows will fail to produce red blood cells and this result to anemia. To save this crisis, blood is usually transfused to them.
SC, SS, or CC are Sickle cell diseases (a recessive disorder) – a very serious medical condition with high prevalence rate in sub Saharan Africa. This is why intending couples must make sure to know their genotype and blood group compatibility before going ahead with marriage.
What is the Genotype and Blood Group compatibility that is good for marriage?
Study this table below carefully:
- AA + AA = AA, AA, AA, AA
- AA + AS = AA, AS, AA, AS,
- AA + SS = AS, AS, AS, AS,
- AA + AC = AA, AA, AA, AC.
- AS + AS = AA, AS, AS, SS,
- AS + SS = AS, SS, SS, SS,
- AS + AC = AA, AC, AS,SS.
- SS + SS = SS, SS, SS, SS,
- AC + SS = AS, AS, SS, SS,
- AC + AC = AA, AC, AC, SS.
Based on the table above, you can see that a person with the genotype AA can marry across. There’s no risk of having a sicklier for a child even when he or she marries an SS. An AA genotype person marrying an SS can only result in AS children. There’s no hope of having a child with the genotype AA. But there’s no danger either.
Someone with the genotype AS should only marry someone with the genotype AA because if AS marries another AS there’s one out of 4 chances (AS, AS, AA and SS) that they will have a child with the sickle-cell disease. Same applies when AC is combined. AC and AS combine will produce AA, AS, AC, SC, the sickle-cell disease will be SC.
Of course there are many cases where two abnormal was combined that is an AS and AS or AC and AC or AC and AS couples and had up to five or six children without a single sicklier among them. But there is no need to risk it? What if you’re not so lucky? Can you forgive yourself when you end up having a child with the sickle-cell disease and put the child through the agony the disease brings when you could have easily avoided it by doing a genotype and blood group compatibility test.
Compatible genotypes for marriage are:
AA marries an AA. That’s the best compatible. That way you save your future children from having to worry about genotype compatibility in future.
AA marries an AS. You’ll end up with kids with AA and AS which is good. But sometimes if you’re not lucky all the kids will be AS.
AS and AS should not marry, you already know what it can lead to.
AS and SS shouldn’t think of marrying.
And definitely SS and SS must not marry since there’s absolutely no chance of escaping having a child with the sickle-cell disease.
The only thing that can change the genotype is an intentional act like Bone Marrow Transplant (BMT) Technology. It has been proven to be the only permanent cure to SS SC and CC; however, it is new, very expensive and cannot be done in any part of Africa. It also carries some risks.
Naturally, environment or time cannot change genotype.
Divine Miracles can change it as well – it has happened in so many part of the world. Again, some SS carriers may start experiencing crisis at late age (as late as 40s). If these set of people go for test in a quack lab, definitely the lab technician will assume AA or AS since the person is not showing the symptoms. Later in life, it will become obvious when the symptoms starts appearing.
BLOOD GROUP COMPATIBILITY
It is advisable that intending couples should know their blood groups before marriage.
The red blood cells that transport oxygen in the body carry two antigens, which are the A and B antigens. These antigens determine the blood group. The blood groups are designated by the letters O, A, B, AB. When the red blood cell carries only the A antigen, the blood group is ‘A’, it is ‘B’ when the blood cell has only the B antigen. When both A and B antigens are present, the blood group is ‘AB’. Finally, when there is neither A nor B antigen, the blood group is referred to as ’O’.
Here is the table that shows a cross breed of different blood groups and their products:
A + A = A or O
B + B = B or O
A + B = A, B, AB or O
A + O = A or O
B + O = B or O
A + AB = A, B or AB
O + O = O only
Blood groups have a hereditary basis and depend upon a series of alternative genes, a fact sometimes utilized in solving the problems of disputed parentage.
Equally important and linked to the blood group is the Rhesus antigen, also known as the Rh Factor, which is positive in 83% of the British population but about 95% among the black population.
You can be O Rhesus positive (O+ve) or O Rhesus negative (O-ve). When an Rh +ve blood is given to an Rh -ve person, then Rhesus antibodies are stimulated; for instance, immunization of a woman can result from blood transfusion or injection of Rh positive blood. In women also, immunization due to pregnancy can result from the passage of the Rh +ve antigen from a Rh positive fetus across the placenta into the circulation of a Rh negative woman.
It must be emphasized that when an Rh-ve woman is married to an Rh positive man, the chance for her becoming sensitized to the Rh antigen and thus having children affected with haemolytic (red cell breakdown) disease of the new-born is relatively small.
The risk of developing antibodies increases with succeeding pregnancies, thus if a Rh-ve woman marries a Rh +ve man, there is 1 in 143 chance of Rhesus iso-immunization during the first pregnancy, 1 in 14 during the 2nd and 3rd; 1 in 12 during the 4th, and 1 in 8 during the 5th pregnancy.
The overall incidence of haemolytic disease of the newborn due to this problem is about 1 in 200 of all pregnancies. Usually, sensitization due to pregnancy practically never results in haemolytic disease in the first child; on the other hand, sensitization due to previous blood transfusion may cause the first child to be affected. Thus the importance of avoiding the transfusion of Rh +ve blood to a Rh -ve person must be emphasized.
In conclusion, in view of the low risk of Rhesus iso-immunization, Rhesus factor does not constitute an absolute contradiction why a Rh -ve woman should not marry a Rh +ve man. Even in the few cases where sensitization occurs, the affected child can still be effectively treated. There is a drug that can be used to prevent sensitization if the Rhesus status of the couple is known initially. There is no risk of Rhesus iso-immunization if both couple are Rhesus +ve, or are Rhesus -ve, or if a Rh -ve man marries a Rh +ve woman.