AB negative blood is the rarest of the eight main blood types, with only about 1% of donors possessing it. While demand for AB negative is relatively low, some rare blood types are both uncommon and highly sought after. However, the rarest blood type overall is Rh-null, also known as "golden blood," with fewer than 50 people worldwide possessing it. This type lacks all 61 known antigens.
Understanding Blood Type Rarity
Several factors contribute to blood type rarity:
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ABO System: The ABO system categorizes blood into A, B, AB, and O types based on the presence or absence of specific antigens. AB negative combines the less common AB type with the less frequent Rh negative factor.
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Rh Factor: The Rh factor is another important antigen. Individuals are either Rh positive (more common) or Rh negative (less common). The combination of a rare ABO type and Rh negative status creates an extremely rare blood type.
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Subtypes: Beyond the main ABO and Rh systems, many other blood group systems exist, leading to further rare subtypes within the already infrequent groups. These subtypes can make finding compatible blood incredibly difficult.
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Rh-null: This exceptionally rare blood type lacks all antigens in the Rh system, making it practically invaluable in transfusions for those with severe Rh system antibodies.
Common Blood Types and Their Prevalence (Approximate Percentages):
- O positive: 35%
- A positive: 30%
- B positive: 8%
- O negative: 13%
- A negative: 8%
- B negative: 2%
- AB positive: 2%
- AB negative: 1%
This data shows that while AB negative is rare among the main blood types, Rh-null is the absolute rarest, with an incredibly low prevalence globally.
