Understanding Blood Type Inheritance

Learn how blood types are passed from parents to children through genetic inheritance

šŸ§¬ How Blood Groups Work

Blood types are determined by alleles - different versions of the same gene. Each person inherits two alleles for blood type, one from each parent.

The Three Main Alleles:

  • A allele: Produces A antigens on red blood cells
  • B allele: Produces B antigens on red blood cells
  • O allele: Produces no antigens (recessive)

Why A and B blood types can have different genetic makeups:

Type A and Type B Blood

Type A can be:

  • AA: Two A alleles
  • AO: One A allele, one O allele

Type B works the same way:

  • BB: Two B alleles
  • BO: One B allele, one O allele

Both A and B are dominant over O, so AO shows as Type A and BO shows as Type B

The Rh Factor (Rh+ and Rh-)

The Rh factor is a separate genetic system that works independently from ABO blood types.

Rh inheritance:

  • Rh+ (positive): Can be DD or Dd (D is dominant)
  • Rh- (negative): Must be dd (both alleles recessive)

Why D and d (not R and r):

The Rh factor is determined by the RHD gene. The D antigen is the most important Rh antigen. Standard genetic notation uses ā€œDā€ for the dominant allele (produces D antigen = Rh+) and ā€œdā€ for the recessive allele (no D antigen = Rh-).

Example: Someone can be A+ (AO with Dd) or A- (AO with dd). The ABO and Rh systems are inherited independently.

ABO Blood Type Inheritance

Select parent blood types below to see all possible outcomes for their children

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Father

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Mother

Educational Tool

This interactive tool demonstrates the principles of genetic inheritance for blood types. It shows all possible outcomes when combining parental blood types according to Mendelian genetics.

Select both parent blood types above to begin the visualization.

Rh Factor Inheritance

Select parent Rh factors below to see how the D antigen is inherited independently

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Father
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Mother

Rh Factor Inheritance

This tool demonstrates how the Rh factor (D antigen) is inherited independently from ABO blood types. The D allele is dominant over d, so Rh+ individuals can be DD or Dd, while Rh- individuals must be dd.

Select both parent Rh types above to begin the visualization.

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