TheScianna blood antigen system consists of sevenantigens.[1][2] These include two high frequency antigens Sc1 and Sc3, and two low frequency antigens Sc2 and Sc4.[1]
The very rare nullphenotype is characterised by the absence of Sc1, Sc2 and Sc3.[1]
The antigens are caused by changes in theerythroid membrane associatedprotein (ERMAP).[3][4]
This blood group system was discovered in 1962 when a high frequency antigen was detected in a young woman (Ms. Scianna) who had experienced several late pregnancy losses due tohaemolytic disease of the fetus.[3]