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In which regions and populations is blood type O especially common?

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Close-up illustration of multiple human red blood cells with their characteristic disc shape, floating against a red background. — blood group The major component of human blood is the red blood cell.

Blood group O is the most common blood type globally. While it is found in all human populations, it is particularly prevalent among the peoples of South and Central America.12

The distribution of blood types, including the frequency of the O gene, varies across different regions due to factors such as genetic drift and natural selection.23