Blood Type Inheritance Calculator

Understanding Blood Type Inheritance

Blood type is determined by genes inherited from both parents. The ABO blood group system involves three alleles: A, B, and O. The A and B alleles are co-dominant, while O is recessive. The Rh factor (positive or negative) is determined by a separate gene.

ABO Blood Group Genetics

Alleles and Genotypes

• Type A: Can have genotype AA or AO
• Type B: Can have genotype BB or BO
• Type AB: Has genotype AB (co-dominant expression)
• Type O: Has genotype OO (recessive)

Inheritance Patterns

Parent 1	Parent 2	Possible Child Types
O	O	O
O	A	O, A
O	B	O, B
O	AB	A, B
A	A	O, A
A	B	O, A, B, AB
A	AB	A, B, AB
B	B	O, B
B	AB	A, B, AB
AB	AB	A, B, AB

Rh Factor Inheritance

The Rh factor is determined by the presence (+) or absence (-) of the D antigen:

• Rh Positive (+): Can have genotype DD or Dd
• Rh Negative (-): Has genotype dd (recessive)

Two Rh-positive parents can have an Rh-negative child if both carry the recessive d allele (Dd x Dd).

Clinical Significance

Blood Transfusions

Matching blood types is critical for safe transfusions. Incompatible blood can trigger life-threatening reactions.

Pregnancy Considerations

Rh incompatibility between mother and fetus can cause hemolytic disease of the newborn (HDN). Rh-negative mothers carrying Rh-positive babies may need RhoGAM injections to prevent complications.

Universal Donors and Recipients

• Universal Donor: O- (can donate red blood cells to anyone)
• Universal Recipient: AB+ (can receive red blood cells from anyone)

Blood Type Distribution

Approximate distribution in the US population:

• O+: 37%
• A+: 36%
• B+: 8%
• AB+: 3%
• O-: 7%
• A-: 6%
• B-: 2%
• AB-: 1%