Blood is a liquid tissue made up of a fluid called plasma,with several blood cells suspended in it,mainly the red blood cells,white blood cells and the platelets.
Red blood cells are tiny flat discs packed with haemoglobin which gives the blood its red colour and the capacity to carry oxygen.Oxygen is supplied to all parts of the body from the lungs for the use of the tissues.
There are many variants of haemoglobin,but the commonest type is haemoglobin A (it is referred to as the usual haemoglobin). The other types are referred to as unusual haemoglobin.
Examples of the unusual types are haemoglobin S (or Hb S), Hb C,and so on.Many of these haemoglobin types do not cause any health problem. A few,like Hb S can cause severe disorder to the bearer's health.
The genes carry the blueprint of life. It is the genes that dictate the colour of our skin,the shape of our nose,the type of haemoglobin,etc.
The haemoglobin genotype dictates the type of haemoglobin our blood cells contain. The type of haemoglobin genotype we bear depends on what we inherit from our parents. For instance,if the father is Hb genotype AS and the mother is Hb genotype AS,the offspring would inherit either Hb A or S from the father and also Hb A or S from the mother.
Only one of the pair can be inherited from the father or mother and together this form your own haemoglobin genotype.Thus,the children of this supposed couple can have Hb genotype AA,AS or SS.
As said earlier, the unusual Hb S can sometimes cause disorder to the health of the bearer. Especially when it is inherited in combination with another unusual Hb,which can be Hb S itself or any other like Hb C;the child is said to have sickle cell disorder.
This is because the Hb S has the tendency of sicking the red blood cells under unfavorable conditions.By sicking I mean the red blood cells become sickle shaped instead of the usual round shape which can cause severe health disorder.
For two young people working towards marriage,it is crucial for them to know their genotype before they they hook up.
It is very important for them to understand what they are getting into. It is always good to make an informed decision. If a person with Hb genotype AS decides to marry someone of the same Hb genotype AS,they must understand that there is 80% probability of having children with Hb AA,AS or SS.
The consequence of this decision is that if they have a child with Hb AS,the child is would be a carrier of unusual haemoglobin. If the child happens to be born with Hb SS,the child has sickle cell disorder and this has implications for the child and the whole family.
Some intending couples called off their marriage plans after they discovered they are both carriers of unusual haemoglobin. They felt they could not face the challenges of having a child with sickle cell disorder.That is their informed decision.
And there are those who after knowing they are both carriers of sickle cell trait(AS),they still went ahead to get married: should they be blessed with a child with sickle cell,they would give it all the love and care they could. That is their informed decision.
It is advisable for couples who intend to get married to know their genotype and seek counsel from a genetic counselor so that whatever decision they make would be an informed one.It is better to know your genotype beforehand so that you'd be prepared for whatever comes your way than not to know your genotype and get what you are not prepared for.
I have heard people say if they love the person enough and genuinely,either they are both Hb AS or one AS and the other SS,they would still get married to the person: trying to draw the line between LOVE and the menace of having a child with sickle cell. I read the story of a woman who is SS and wanted to marry a man with Hb AA at all cost to avoid having any offspring with sickle cell.
She eventually got one and the marriage was blessed with children.But she got divorced after some years.WHY? Who knows?
Life is full of choices.Who you are today is as a result of the choices you made yesterday.Your tomorrow depends on the choice you shall make today.
What are ABO blood groups?
Blood types are classified in several ways. The most basic system is called ABO, which divides blood into four groups, or types: A, B, AB and O.
There are two distinct antigens (a type of protein) present on the surface of some people's red blood cells. Each person's blood contains a specific and inherited set of these.
In the ABO system, one antigen is labeled "A" and the other "B." If the red blood cell has only A antigen on it, that blood is called "type A". If the red blood cell has B antigen only, that blood is called "type B". If the red blood cell has both A and B antigens, the blood is called "type AB". If the red blood cell has neither antigen, the blood is called "type O".
In a group of 100 people, on average:
45 are type O
40 are type A
0 are type B
5 are type AB.
This varies among different ethnic populations. A small percentage of people have rare blood types, which appear as an unusual and sometimes extensive series of letters in addition to their ABO type.
A blood type is considered rare when more than 200 donors have to be screened to find one compatible donor.
Blood types and parentage
Because the antigens on the red blood cells are controlled by genes, you can determine the possible blood types of children produced by a given pair of parents.
Each person receives an A, a B, or an O gene from each parent. In this system the A and B genes are co-dominant (equally dominant), and the O gene is recessive.
This means that a person whose genetic type is either AA or AO will have blood type A; those with genetic type BB or BO will have blood type B, and those with genetic type OO will have blood type O.
Blood tests can also be used when trying to determine paternity, or rather to exclude some men from being the fathers of some children. For instance, if the parents both have blood type O, then the children must all have blood type O.
If a child were to have blood type A, B, or AB, then the presumed father cannot be the real father. If the child's blood type was O, then the presumed father could be the real father - but so might millions of other men, so this is certainly not conclusive proof. The table lists possible and impossible situations:
Parents' Blood Types
Possible Children
Impossible Children
A & A (genetically AA/AO & AA/AO)
A, O
B, AB
A & B (genetically AA/AO & BO/BB)
A, B, AB, O
none
A & AB (genetically AA/AO & AB)
A, B, AB
O
A & O (genetically AA/AO & OO)
A, O
B, AB
B & B (genetically BB/BO & BB/BO)
B, O
A, AB
B & AB (genetically BB/BO & AB)
A, B, AB
O
B & O (genetically BB/BO & OO)
B, O
A, AB
AB &AB
A, B, AB
O
AB &
A, B
AB, O
O & O
Medical Genotype Chart Table For Intending Couple
Genotype
|
Possible Combination
|
Remark
| |||||||||||
|
Partner X
|
Partner Y
| ||||||||||||
|
AA
|
AA
|
AA
|
AA
|
AA
|
AA
|
Can Marry
| |||||||
|
AA
|
AS
|
AA
|
AS
|
AA
|
AS
|
Can Marry
| |||||||
|
AS
|
AS
|
AA
|
AS
|
AS
|
SS
|
Not to Marry
| |||||||
|
SS
|
AA
|
AS
|
AS
|
AS
|
AS
|
Can Marry
| |||||||
|
SS
|
SS
|
SS
|
SS
|
SS
|
SS
|
Not to Marry
| |||||||
|
AS
|
SC
|
SS
|
AS
|
AC
|
SC
|
Not to Marry
| |||||||
|
AS
|
CC
|
AC
|
AC
|
SC
|
SC
|
Not to Marry
| |||||||
|
AA
|
SC
|
AS
|
AC
|
AS
|
AC
|
Can Marry
| |||||||
|
AA
|
CC
|
AC
|
AC
|
AC
|
AC
|
Can Marry
| |||||||
Note: Three major groups of genotype are: AA (Normal); AS (Carrier), SS (Sickler). Others are SC AND CC.
| |||||||||||||
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