ABO Blood Types in Humans

 

The following table gives information on human blood types. Alleles of types IA and IB are dominant over type i.

Genotype

Blood Type

Blood Proteins

Blood Antibodies

i i

Type O

None

Anti-A and Anti-B

IA IA

Type A

A

Anti-B

IA i

Type A

A

Anti-B

IB IB

Type B

B

Anti-A

IB i

Type B

B

Anti-A

IA IB

Type AB

A and B

None

Because Blood type O contains no proteins that could be rejected, O is sometimes referred to as the universal donor. Because Type AB has all possible proteins, none will be seen as foreign so AB is the universal recipient.

The following table shows the distribution of blood types in the human population.

ABO Type
Rh Factor
% in Population
Combined %
O
+
38.4
46.1
-
7.7
A
+
32.3
38.8
-
6.5
B
+
9.4
11.1
-
1.7
AB
+
3.2
3.9
-
0.7

Differences in the frequency of blood types in different populations of humans are presumably due to historical isolation of small populations, which led to genetic drift. For an interesting article on misconceptions about race and human differences, read R.C. Lewontin.