Genetics of Blood Groups: How Inheritance Determines Your Blood Type

Blood mainly consists of four components –

• Red blood cells, which work to carry oxygen throughout the body.
• White blood cells, which play an important role in the body's immune system.
• Plasma, which is a yellow colored liquid. It mainly contains proteins, which help in maintaining the proper functioning of the entire body.
• Platelets, which work in blood clotting.

Blood group mainly depends on antigens and antibodies, which are a type of protein molecules. Antigens are on the surface of red blood cells, while antibodies are in plasma. These two together determine the type of blood.

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There are mainly four types of blood groups and doctors call it the ABO system. These groups are as follows

• Blood Group A – It contains A antigens and B antibodies in red blood cells.
• Blood Group B – It contains B antigen and Antibodies.
• Blood Group O – It has no antigen, but has both A and B antibodies.
• Blood Group AB - This blood group has both A and B antigens, while neither has antibodies.

Apart from A and B, there is also a third type of antigen, which is called Rh factor. If someone has this Rh factor in his blood, it means that he is Rh positive i.e. his blood group is positive. At the same time, the person whose blood does not have this antigen is RH negative i.e. his blood group is negative. On this basis, there are total 8 types of blood -

• Blood Group A Positive
• Blood Group A Negative
• Blood Group B Positive
• Blood Group B Negative
• Blood Group O Positive
• Blood Group O Negative
• Blood Group Ab Positive
• Blood Group Ab Negative

(Read more - Blood Test)

We have tried to explain below which blood can be given to which person -

• A positive – This is the most common blood group. A person of this group can donate his blood to a person of A positive and AB positive group.
• A Negative – This is considered a rare blood group. If a person is A negative, then he can donate his blood to any type of A and AB group person.
• B Positive – A person of this group can donate blood only to B positive and AB positive people.
• B Negative – A person of this blood group can donate his blood to any person with B and AB blood type.
• AB Positive – People with this rare blood group can receive any type of blood or plasma. These are known as universal recipes.
• AB Negative – This is considered to be the rarest blood group and the number of people in this group is also less. Someone with this type of blood is known as a "universal plasma donor", because this type of plasma can be given to anyone.
• O Positive – This is one of the most common blood types. With this, blood of any positive blood group can be given.
• O Negative – A person with this rare blood group can donate blood to anyone with any blood group.

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To identify blood groups, lab technicians mix a blood sample with antibodies that attack A and B blood to see how it reacts. Let us now know how blood group is identified -

• To know the blood group, red blood cells are mixed with different antibody solutions. If there are B antibodies in the solution and B antigens in the cells, it means blood group is B.
• If the blood does not react with either anti A or anti B, it means the blood is group O.
• Blood groups can be identified through similar blood group tests, in which antibodies are used.

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Most people are capable of donating blood. For that it is necessary to fulfill the following criteria -

• It is important for a person to be fit and healthy.
• The weight of the person should be at least 50 kg.
• The age of the person should be between 17 to 66 years.
• If the age is more than 70 years, then blood should have been donated at least 2 years ago.

(Read more - Blood Culture Test)

The ABO system is best in blood type. There are about 8 types in this system, out of which O positive is a common type and AB negative is the least common blood type. If blood transfusion is required, the blood types of both the blood donor and the blood recipient should match, so that any type of complication can be avoided.