Two New Examples of Hb St. Etienne [β 92(F8)His→Gln] in Association with Venous Thrombosis

Hb St. Etienne [β92(F8)His→Gln] (also known as Hb Istanbul) is a rare unstable β-globin chain variant that has been described in only three reports involving four patients. We report two individuals in a family of Scottish extraction whose members had been erroneously diagnosed to have hereditary spherocytosis (HS) and have now been shown to be heterozygotes for Hb St. Etienne. They also had venous thrombotic events with minimal provocation. This family illustrates the difficulties in identifying the cause of chronic hemolytic anemia and highlights the possible contribution of chronic hemolysis to increased risk of thrombosis.