Abstract
Hemoglobin (Hb) is a tetrameric molecule made up of two alpha and beta globin subunits. It exists in erythrocytes in the blood stream of vertebrates, taking charge of gas exchanges between the lung and the peripheral blood tissues. Carrying and supplying oxygen to body tissues its the most important role of Hb, which is largely influenced by it oxygen affinity. Lowered oxygen affinity is reported to increase the release of oxygen from Hb molecules to peripheral tissues and to improve the tissue oxygenation. Over 1,000 kinds of Hb variants have been characterized clinically and some variants show lowered oxygen affinity, among which are two novel ones, Hb Titusville and Presbyterian.