Technically, there is no such type a A2 positive. You are either A positive or not. However, if this is supposed to indicate a person who is homozygous for type A in his genotype, that could explain the number because it would mean that the person's genotype is AA, or two dominant alleles for this type.
Let's look at blood types:
There are two possible antigens on the red blood cell, type A and type B. They have no function, but they are either there or they are not, and that is determined by genetics. If you have neither antigen, you are type O (as in zero). Since these genes are both co-dominant over type O, if you have one of each, you will have both antigens on your RBCs and you'll be type AB.
Positive refers to the rhesus factor, another protein found in the plasma. About 85% of the human population has this protein, making them rh+. If they do not have the protein, they are rh-. This is also determined by genetics, but it is a different allele from the A or B gene.
A person with A+ blood has the type A antigen on his RBCs and the rhesus protein in his blood plasma.
A person can be type A with two possible genotypes: he can be AA, or AO. AO means that he still has type A antigens in his blood, but he also carries the recessive gene for no antigens, or type O, which can be passed down to his offspring.
The importance is that if blood is transfused into someone who does not have that antigen in his blood, it will most likely kill him because his antibodies will see the foreign antigen as an enemy and will attack it, causing RBCs to coagulate in the blood stream.
This is why it is important to know one's blood type.
My father was O+, my mother A+. My brothers and I are all A+, so my mother was most likely (but not definitely) a homozygous type A, meaning she only had A genes to donate. She could have been AO and none of us got her O gene; it's difficult to say.
However, I know that I am AO (type A, carrying an O gene) because my dad could only donate O genes (type O is OO, always), so I know I carry that genotype.
The rh factor is similar. If rh + blood is given to an rh- person, the same clotting by antibodies will occur.
Let's look at blood types:
There are two possible antigens on the red blood cell, type A and type B. They have no function, but they are either there or they are not, and that is determined by genetics. If you have neither antigen, you are type O (as in zero). Since these genes are both co-dominant over type O, if you have one of each, you will have both antigens on your RBCs and you'll be type AB.
Positive refers to the rhesus factor, another protein found in the plasma. About 85% of the human population has this protein, making them rh+. If they do not have the protein, they are rh-. This is also determined by genetics, but it is a different allele from the A or B gene.
A person with A+ blood has the type A antigen on his RBCs and the rhesus protein in his blood plasma.
A person can be type A with two possible genotypes: he can be AA, or AO. AO means that he still has type A antigens in his blood, but he also carries the recessive gene for no antigens, or type O, which can be passed down to his offspring.
The importance is that if blood is transfused into someone who does not have that antigen in his blood, it will most likely kill him because his antibodies will see the foreign antigen as an enemy and will attack it, causing RBCs to coagulate in the blood stream.
This is why it is important to know one's blood type.
My father was O+, my mother A+. My brothers and I are all A+, so my mother was most likely (but not definitely) a homozygous type A, meaning she only had A genes to donate. She could have been AO and none of us got her O gene; it's difficult to say.
However, I know that I am AO (type A, carrying an O gene) because my dad could only donate O genes (type O is OO, always), so I know I carry that genotype.
The rh factor is similar. If rh + blood is given to an rh- person, the same clotting by antibodies will occur.
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The A blood group can be subdivided into A1 and A2.
A2 red cells have approximately 20-25% less A antigen than A1 cells. In addition to this quantitative difference, A1 and A2 antigens have a different carbohydrate composition. This biochemical difference may explain why 1-8% of A2 individuals and 22-35% of A2B individuals produce anti-A1 antibody.
A2 red cells have approximately 20-25% less A antigen than A1 cells. In addition to this quantitative difference, A1 and A2 antigens have a different carbohydrate composition. This biochemical difference may explain why 1-8% of A2 individuals and 22-35% of A2B individuals produce anti-A1 antibody.
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Its a type of blood