Pyruvate kinase variants characterized by the methods recommended by the International Committee for Standardization in Haematology.

Seven new pyruvate kinase (PK) variants were characterized by the recently established recommended methods by the International Committee for Standardization in Haematology (ICSH). The seven cases were all true homozygotes as evidenced by consanguineous marriages of the parents. All of them were Japanese. These variants were designated PK Tokyo, Nagasaki, Sapporo, Maebashi, Itabashi, Fukushima, and Aizu. Low substrate affinity for phosphoenolpyruvate and thermal instability seem to play a major role in causing clinical manifestation of chronic hemolysis. Product inhibition of PK by ATP may also play an additional role in some cases.