Hb Uxbridge [β20(B2)Val → Gly]: A New Variant with Mild Incre in Oxygen Affinity Found During A Neonatal Screening Program

Abstract

Hb Uxbridge [β20(B2)Val → GIy] was found in an English family during a neonatal hemoglobinopathy screening program. In both the child and the parent carrying this hemoglobin variant, the red cell parameters were normal. By isoelectrofocusing Hb Uxbridge appeared to have an isoelectric point slightly higher than Hb A but was silent on cellulose acetate and acid gel electrophoresis. Structural modifications affecting position β20(B2) have been demonstrated to be responsible for a high oxygen affinity and polycythemia in Hb Olympia (Val → Met) and Hb Trölhattan (Val → GIu). In the case of Hb Uxbridge, despite an alteration of the same site, the oxygen binding parameters of the patient's hemolysate showed only a mild (ca. 20%) increase in oxygen affinity.