Blood groups, Hb Genotype & its Effects on Marriages

Blood Genotype

Are you ready to get married, but confused on if you guys are good to go maybe due to your blood group or genotype? Then, this is for you.

Over the past week, a large number of Nigerians on our various platform has been bothered about their status & that of their partners, and most importantly, if they are a good match (or good to go as many would say it).

My Genotype is XXXXX, Can I marry someone with XXXXX?
First & foremost, before we begin to go indept on the matter at hand, let us state it critically that Anyone can marry Anyone, depending on your financial status, and with proper counselling. When we go forward, you’d understand why this was said.

What is Genotype?
Your genotype is your complete heritable genetic identity; It is your collection of genes. These genes’ DNA is used to make protein which forms your entire body.
In Simple English, your genotype is the origin of those features that your inherited from your parents. It is the reason why you look like your father/mother, why you have your complexion, height, weight, etc.

Examples of genotype are the genes responsible for:
eye color, hair color, height, how your voice sounds, certain diseases (e.g, breast cancer, Diabetes), certain behaviors (e.g: some kinds of epilepsy).

This is why a short man, or Lady would be looking for a tall partner to marry to see if they can change that.

The genotype us the reason why if a persons has Breast cancer, or Diabetes, or Asthma, etc, the persons child is also likely to have it, if they inherit those particular set of genes responsible for it.

For more explanation, you can ask questions by comments below. We would love to keep this simple, and today, our focus is on Haemoglobin Genotype or what most persons would call Blood genotype.

What is Haemoglobin Genotype/Blood Genotype?
Like we described above, Haemoglobin genotype is a type of gene combination that is found in the blood (red blood cell). It is a combination, inherited from both parents (father & mother).

What are the types of Hb Genotype?
There are different types of HB Genotype: like A, S, D, E, & C, but our focus today is on A & S.
the Hb-A genotype: this is the normal genotype. Other abnormal types are due to mutation (changes) which are then inherited & transferred to the children.
The Hb-S genotype: this is an abnormal genotype, and is the cause of the popular Sickle cell anaemia. This is the most common abnormal genotype on our environment because it gives some form of protection against malaria which is prevalent here.

What type of Genotype can I get married to?
All types of Genotype is suitable for marriage but to be on the safe side:
AA (normal)– can marry anyone, from AA to SS. If they marry AA, they would give birth to all Normal (AA) children.
If they marry an AS (carrier) person, they would give birth to a possible combination of AA (normal) or AS (carrier).
If they marry an SS (sickler) person, they would give birth to all Carriers (AS).

AS (carriers): advised to marry AA partners, so as to remove the risk of giving birth to Sicklers.
If they marry an AS partner, there is a 25% (1 in 4) chance of giving birth to a normal (AA) person, 50% (2 in 4) chance of having an AS child and 25% (1 in 4) chance of having a Sickler (SS). Know that this doesn’t mean that 1 in every 4 of your child must be a sickler or normal.
No. Its just a probability. This means that it is possible for all your children to be normal (AA), just the same way it is possible for all your children to be Sicklers (SS).

Now, if a person with AS marries someone with SS, they have a 50% chance of giving birth to a child with AS (carrier) and 50% chance of giving birth to a sickler (SS).
Again, this means that, all your children might be carriers, or all of them may be Sicklers.
You can ask more question by comment below if you are confused, and our doctors would respond to your as soon as possible.

SS (Sicklers): for the best case scenario, a person with this genotype should only marry a partner with AA.
In simpler language: the AA’s are the only one that an SS can marry & give birth to normal children (carriers). Any other combination is a risk for giving birth to Sicklers (SS). An SS should never marry an SS, unless they are willing & ready to raise all Sicklers.

For more about Sicklers, read our discussion on Sickle Cell anaemia here.

What if we are in love, & have come too far to go back now?
Every advice here is medically speaking. Love would not change your genotype. Parting ways might be the most difficult thing you can do now, but you both would be grateful in the end.

How can I Change my Genotype?
It is important to know that a genotype can never be changed. It is hereditary & does not ever change. If a person has had 2 different genotype results in the past, its most likely a laboratory error. It is important in our environment to repeat your tests in 3 different labs, one of which should be in a tertiary institution.

Now let’s talk about blood groups.

What is blood groups?
Blood group just like Hb genotype are inherited from the parents. They represent antigens on a blood cell. Just like colouring in a food or drink.

What are the types of blood group?
There are different types of blood groups, but the one we are concerned with today is the ABO group & the rhesus group. This is the most common & important of all.

The different possible ABO blood groups combination are A, B, AB and O. While the rhesus type/factor is the + or – you hear when the blood group are mentioned. Like A+ or B- (that means blood group A, rhesus positive. Or blood group B, rhesus negative).

I am blood group XXXXX, can I marry a person with blood group XXXX??
Unlike the case of genotype, in blood group you can marry anyone regardless of their blood group. There is no problem anywhere.
The major reason why people consider blood groups in marriage is due to 2 things;

  1. If the woman is Rhesus negative: this means if the woman has A-, B-, AB- or O-. If a woman with any of these blood groups marry a man that is positive (A+, B+, O+), she would risk having successive miscarriages from the 2nd pregnancy onwards due to what is called Sensitization. To prevent this, there is a drug that would be given to the woman after every pregnancy so that, she would not have these miscarriages. So, both persons can marry, but this factor should be always remembered.
  2. For possible blood transfusion in future: if for any reason after marriage, there is a need for surgery or urgent blood transfusion, if the blood type are not a match or no one is O- (or O+ if others are positive), then, they would have to seek for blood donors externally.

With the exception of this, your blood groups should not be an obstacle for your marriage to the love of your life (other factors being constant).

We would stop here for today. Feel free to ask any questions you have below, and our doctors would respond to them as soon as possible.

The post would be continually updated whenever necessary.


  • Obasi Chinedu David attended the College of Medicine, University of Nigeria Teaching Hospital, in ituku-ozalla, Enugu state, Nigeria.

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