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Blood Type A

The genotype (allele combination) of a person with blood type A could be AA or AO. Based on the law of independent assortment, the allele combinations AA and AO will be separated eqally during meiosis. In other words, for a male with blood type A and alleles AO, 50% of his sperms are genotype A, and 50% are genotype O, while 100% are A if he has alleles AA. For female, the eggs have the same pattern. Children of two blood type A parents may have 93.75% frequency to be blood type A (AA or AO genotype), and 6.35% frequency to be blood type O (OO genotype). For detailed calculation, see Blood Type Calculator page.

Children Blood Type Frequency Chart

• Blood type A + A:
 Parent Blood Type (A) A (75%) O (25%) ParentBloodType (A) A (75%) A/A (56.25%) A/O (18.75%) O (25%) O/A (18.75%) O/O (6.25%)
Children Type A (AA, AO) = 56.25% + 18.75% + 18.75% = 93.25%
Children Type O (OO) = 6.25%

• Blood type A + B:
 Parent Blood Type (B) B (75%) O (25%) ParentBloodType (A) A (75%) A/B (56.25%) A/O (18.75%) O (25%) O/B (18.75%) O/O (6.25%)
Children Type AB = 56.25%
Children Type A (AO) = 18.75%
Children Type B (BO) = 18.75%
Children Type O (OO) = 6.25%

• Blood type A + AB:
 Parent Blood Type (AB) A (50%) B (50%) ParentBloodType (A) A (75%) A/A (37.5%) A/B (37.5%) O (25%) O/A (12.5%) O/B (12.5%)
Children Type A (AA,AO) = 37.5% + 12.5% = 50%
Children Type B (BO) = 12.5%
Children Type AB = 37.5%

• Blood type A + O:
 Parent Blood Type (O) O (100%) ParentBloodType (A) A (75%) A/O (75%) O (25%) O/O (25%)
Children Type A (AO) = 75%
Children Type O (OO) = 25%

ABO blood group system can be used together with Rh blood group system, the later can be + or -. Blood type A can be A+ or A-.

Blood type A+ can accept blood from A+, A-, O+ and O- Donor's red blood cell.
Blood type A+ can accept blood from A- and O- Donor's red blood cell.
Blood type A+ donor's red blood cell can only be accepted by A+ and AB+ recipients.
Blood type A- donor's red blood cell can be accepted by A+, A-, AB+ and AB- recipients.

Blood type A can accept blood from A and AB Donor's plasma.
Blood type A donor's plasma can be accepted by blood type A and O recipients.

Blood type A has higher frequency in Europe, Australia and East United States/Canada, where about 35-40% of the population are type A. Blood type A frequency is especially lower in Latin America, where <5% of the population are type A. Africa and South, East Asia have lower blood type B frequency too, where about 15-20% of the population are type A.