An update on the Knops blood group system.

This update of the Knops (KN) blood group system (Moulds JM. The Knops blood group system. Immunohematology 2010;26:2-7) adds no new antigens to this system (International Society of Blood Transfusion system 22), which currently has nine antigens. However, the molecular basis of York, KN5, or Yka has been identified as c.4223C>T and designated KN*01.-05. Although not considered clinically significant in the field of transfusion medicine, there has been great interest in the Knops polymorphism by investigators working on malaria documented by numerous studies over the past 8 years.