Blood Group and Genotype Compatibility before Marriage

Blood group can also be called blood type.

Before the advent of advanced scientific and technological approach to determining blood group mostly in Africa.

Many people never took into considerations the risky implications of getting married and giving birth to children without first testing to ascertain the compatibility of their blood types and genotype.

The ignorance and negligence of this aspect of this medicine led to the reproduction of offspring who ends up losing their lives because of sickle cell anemia.

The death of these children was something we had no explanations for until the advent of the genotype and blood group testing techniques which requires intending couple to undergo a medical testing to determine their blood group and genotype.

It is very important to know that genotype and blood group are two different medical terms that means different things.

 What is genotype?

The genotype of an organism is the chemical composition of its DNA (deoxyribonucleic acid) which gives rise to its phenotype, or the total observable trait of the individual.

Genotype is much like the code which runs a computer software application. It is the DNA that an individual inherits from ones parents.

Genotype is different from phenotype, while genotype is your complete heritable identity; Phenotype is the total description of your physical features.

For instance; examples of genotype are the genes responsible for;

  • Hair color
  • Behaviors
  • Height
  • Eye color
  • The color stripes on a cat
  • A person’s shoe size

Examples of phenotype are the exact things you see on the individual while genotype refers to the gene that causes the manifestation of those characteristics;

  • Eye color
  • Hair color
  • Height
  • Behaviors
  • A persons shoe size

We have taken time to explore the difference between genotype and phenotype so you could understand that in as much as the two words sound alike; they do not mean the same.

So now let’s look at the different genotypes we have in humans and how they affect couple compatibility.

The genotypes include;


I never knew there is a genotype like AC until I read an article, I guess may be because this particular genotype is not popular.

In our blood the dominant thing in there are cells and red blood cell are the most abundant.

These red cells contains haemoglobin,which is a substance which maintains and sustains the red blood cells haemoglobin comprises two parts ;The heme part which is the part containing iron complex and a globulin part which is the important part and it’s a protein.

We also need to know that hemoglobin is made up of 2 alphas and 2 beta globulin-protein chain. This is the normal chain in a hemoglobin problem arises when there is any alteration in either of the chains more especially in the globulin chains.

Matching genotype and blood group for marriage

Genotype AA:

People with the genotype AA can marry across all the other genotypes.

There is no risk of giving birth to a child with sickle cell anaemia even when they marry SS

When the genotype AA marries SS (sickle cell carrier) the result will only be SS children. There is no chance of having children that is SS but again there is no risks of having sicklers.Do you say AA is the best shot? Yes it is!

Genotype AS:

People with the AS genotype should only look out to marry people with AA.

If they get married to either AS OR AA there is always 25% probability that will give birth to sicklers.The same thing happens when AC is combined with AC.

In the case of AS, AC, SC the sickle cell disease will be SC.

Not to forget that I have encountered a situation where two people having the abnormal genotype AS married each other and had up to six children with no single SS among them. But wait! Why risk it?

What if you are not so lucky and end up with an SS child.

Can you bear the pain of watching the child suffer all through his life? When you could have easily avoided it.

It’s difficult especially when you are already deep in love with the person in question. But in all you have to let go for the future of your kids.

In summary

  • AA marrying AA is the best option.

All your kids will be AA without any alteration in their genotype.

  • When AA marries AS .You will end up with kids, with AA and AS which is good but if you are not lucky all of them could be AS, although there is nothing wrong with the kids being AS but what if they marry AS?
  • AS and AS should not marry.
  • AS and SS should not marry.
  • SS and SS should not marry.

What is blood group?

This is a classification of the blood in the human body based on either the presence or absence of antibodies and also based on the presence or absence of inherited antigenic substances on the surface of Red blood cells.

Antigens can be proteins or glycolipids.

When blood from two individuals is mixed, sometimes agglutination or clumping of the red blood cells occurs.

The agglutination is caused by immunological reactions.

This clumping was observed in some cases but not present in other cases, this remained a mystery to scientists until blood groups were discovered by the Austrian scientist called Karl Landsteiner in 1901.

There are many blood group systems which includes;

  1. ABO system
  2. MNS blood group
  3. Lewis blood group
  4. Auberger groups
  5. Diego group
  6. Bombay groups
  7. Duffy groups
  8. Lutheran group
  9. Rhesus system

The knowledge of blood group also aids in blood transfusion and other surgical procedures.

How to determine the ABO blood group

The determination of the ABO blood group depends on the immunological reactions between antigen and antibody.

Two antigens were found on the surface of red blood cells; these two antigens are called antigen A and antigen B.

These antigens are called agglutinogens due to their ability to cause agglutination or clumping of blood cells.

There is also the presence of antibodies or agglutinins in the plasma which are called Antibody A and Antibody B.

However, a particular antigen and antibody cannot be present in the blood at the same time.

If this occurs then agglutination of blood is inevitable.

The ABO blood group

Based on the presence or absence antigen A or antigen B, blood is divided into four major groups;

  1. A group
  2. B group
  3. AB group
  4. O group

“A” group

Blood having antigen A belongs to this group. They have antibody B in the serum.

People in blood group A should not receive blood from group B because their Anti B antibodies will attack the group B cells.

“B” group

Blood having antigen B belongs to this group.

People who have group B should not receive blood from group A because their Anti A antibodies will attack the group A cells

“AB” group

If there is the presence of both antigen A and antigen B, the blood group is AB group. There is no antibody in the serum. People who belong to this group are called “Universal Receivers”, that is to say that they can receive blood from all the other groups.

“O” group

In this type of blood group, the antigen A and B are absent while antibodies A and B are present. People who have this blood group are referred to as “Universal donors”.

That means that they can donate blood to all other blood groups. But they must be rhesus negative before they can donate.

The rhesus blood group incompatibility poses serious complications during pregnancy and child birth; this is why people should know their blood groups before getting married.

In our next chapter we shall discuss the Rhesus blood group and the complications in detail. Do not miss out

Importance of knowing blood group

Nowadays, knowledge of blood groups is very essential, medically, socially and judicially. The importance includes;

  1. Medically its important during blood transfusion and tissue transplants
  2. Socially one should know his or her own blood group and become a member of the blood donors club so that he or she can donate blood when approached
  3. Generally the knowledge of blood group is very important because it helps to prevent incompatibility and save the child from disorders like erythroblastosis fetalis
  4. It helps in medico-legal cases to sort out parental disputes



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