Hemoglobin-Seattle (α₂^Aβ₂^{76 Glu}): An Unstable Hemoglobin Causing Chronic Hemolytic Anemia

Mild to moderate chronic hemolytic anemia in a mother and her two sons was found to be associated with the presence of about 40 per cent abnormal hemoglobin of rapid electrophoretic mobility: Hb-Seattle. Hb-Seattle was found to be unstable in vitro. It was shown to be due to a replacement of alanine by glutamic acid at position 76 of the β hemoglobin chain. The substitution occurs at the surface of the β hemoglobin chain. The hemoglobin instability was attributed to an abnormal interaction between the substituted glutamic acid and histidine at position β⁷⁷.