The Indian blood group system (In) is a classification of blood based on the presence or absence of inherited antigens that reside within the CD44 molecule that is expressed on the surface of blood cells.
[1] It is named so because 4% of the population in India possess it.
[2] Most individuals express the Inb antigen that results from an arginine residue at position 46 of CD44 .
The Ina blood type results from a substitution proline for arginine at this same position.
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