Hemoglobin Okayama [beta 2 (NA 2) His replaced by Gln]: a new 'silent' hemoglobin variant with substituted amino acid residue at the 2,3-diphosphoglycerate binding site.

A new 'silent' abnormal hemoglobin, Hb Okayama [beta 2 (NA 2) His replaced by Gln], happened to be discovered in a diabetic Japanese female living in Okayama Prefecture, Japan, in the course of glyco-Hb measurement of the blood samples of diabetic patients. This variant did not differ from Hb A by conventional electrophoretic tests. Only the isoelectric focusing on PAG plate for the determination of glyco-Hb and the cation exchanger chromatography were successful in the separation of this abnormal variant from Hb A and glyco-Hb. Functional study of the whole blood demonstrated a slight increase of oxygen affinity.