While development of genetics in the world of Æthereal Sun has been very incomplete due to the extreme complexities of intra-cellular alchemical processes that determine inheritance of traits, the practical knowledge of blood types is quite solid.
Currently there are 7 known antigens. Some antigens are always present in the blood cells of certain demographics, while others are never present and yet others are optional.
A B C D K L M Khæn + ? ? Nariyása ? ? + Pure Sírkin Tebríthan ? ? Wejít + ? ?
A + denotes that the antigen is always present in a member of a given demographic, a ? indicates that it may be present or not in a given individual. Otherwise the antigen is never present.
Possible combinations of said antigens produce the following blood types:
Khæn: K, KL, KM, KLM. Nariyása: ABC, AC, BC, C. Pure Sírkin: 0 Tebríthan: 0, C, D, CD. Wejít: A, AB, AC, ABC.
Non-pure Sírkin always inherit the mother's blood type and thus fall into Nariyása or Wejít groups for all purposes. However, purely for purposes of identification, Sírkin blood does have a few distinct biochemical markers (this has no effect on compatibility of transfusions).
The Khæn used to have a 0 blood type of their own (without the K antigen), but it was recessive and already very rare during its discovery, and there have been no cases of testing revealing any individuals to have such a type for generations. It should also be noted that the Khæn are so biochemically distinct from other races that attempts of transfusions between the two is lethal or borderline so, even between two type 0's. Also, the ancient Khæn code strictly warns against mixing vital fluids with the non-Khæn, so they would not consent to such a procedure even if it were feasible.