Blood Typing Facts and Statistics

What does forward blood typing mean?

In forward typing a sample of the blood is mixed with serum that contains antibodies against type A blood ("anti-A serum"). Another sample of blood is then mixed with serum that contains antibodies against type B blood ("anti-B serum"). Finally another blood sample is mixed with serum that contains antibodies against type Rh Positive Blood ("anti-Rh serum). Patterns of clotting are then observed and recorded as follows:

Type A blood clots when mixed with anti-A serum.
Type B blood clots when mixed with anti-B serum.
Type AB blood clots when mixed with both anti-A and anti-B serums.
Type O blood does not clot when mixed with either anti-A or anti-B serum.
Rh-positive blood clots when mixed with anti-Rh serum.
Rh-negative blood does not clot when mixed with anti-Rh serum.

What does the above mean for transfusions?

Persons with type A blood can receive blood transfusions from donors with type A or type O blood.
Persons with type B blood can receive transfusions from donors with type B or type O blood.
Persons with type AB blood can receive transfusions from donors with type AB, type A, type B, or type O blood.

Statistically, what is the Blood Type Frequency percentage?

Blood Type frequency in percentage of total population:

Blood Type % Frequency
O 46%
A 40%
B 10%
AB 4%

What about the statistical percentage of Blood Type and Rh factor?
The overall statistical distribution of blood type plus Rh factor in the total population is as follows:

Blood Type Abbr % Frequency
O Rh-positive O+ 38%
O Rh-negative O- 7%
A Rh-positive A+ 34%
A Rh-negative A- 6%
B Rh-positive B+ 9%
B Rh-negative B- 2%
AB Rh-positive AB+ 3%
AB Rh-negative AB- 1%

Note: Percentage distribution may be different within specific racial and ethnic subgroup

If both parents' blood type is known, what are the possible blood types of their children?

Blood type is determined by the "alleles" that are inherited from the parents. Alleles are possible types of a particular gene, in this case the blood type gene. There are three basic blood type alleles: A, B, and O. Children have two alleles, one inherited from each parent. The possible combinations of the three alleles are OO, AO, BO, AB, AA, and BB.

Blood types A and B are called co-dominant alleles, while O is recessive. A co-dominant allele is apparent even if only one is present; a recessive allele is apparent only if two recessive alleles are present. Since blood type O is recessive, it is not apparent if the person inherits an A or B allele along with it. Therefore, the possible allele combinations result in a particular blood type in this way: