Blood types and their inheritance

In short: Blood types are defined by specific sugar molecules on the surface of red blood cells, mainly according to the ABO system and the Rhesus factor. They are inherited from parents according to fixed genetic rules.

In more detail: The ABO system distinguishes blood types A, B, AB, and O, depending on the antigens present on the cells.

In detail

• ABO system: Blood types A and B each carry a specific antigen, AB carries both, and O carries neither.
• Rhesus factor: In addition to the ABO group, the Rhesus antigen determines whether someone is Rhesus-positive or -negative.
• Inheritance rules: Each parent passes on one of two alleles, making certain blood type combinations in children impossible.
• Blood transfusion: Incorrect blood type combinations in transfusions can trigger severe, life-threatening reactions.
• Universal donor and recipient: Blood type O negative is considered the universal donor, AB positive the universal recipient.
• Pregnancy: A Rhesus-negative mother with a Rhesus-positive child requires special medical monitoring.
• Frequency differences: The distribution of blood types varies considerably by world region and ethnic background (dna-und-gene, vererbung-und-mendelsche-regeln).