HB Mississippi [β44(CD3)SeråG]: A New Variant with Anomalous Properties

Abstract

Hb Mississippi was discovered in a 6-year-old Chinese girl with chronic anemia and thalassemia intermedia. Family studies revealed that she had inherited the Hb Mississippi from her father as well as inheriting a gene for β⁺-thalassemia from her mother. Electrophoretic analyses of the hemolysate of the father of the father and the proband on polyacrylamide gels at pH 8.6 showed that the abnormal hemoglobin had three distinct mobilities. A similar pattern was also observed by isoelectric focusing. In addition, multiple abnormal peaks were observed by high performance liquid chromatographic hemoglobin separations as well as high performance liquid chromatographic globin chain separation. Structural analysis of the abnormal hemoglobin demonstrated a single abnormality; the substitution of serine to cysteine at position 44 (CD3) of the β-globin chain. Since CD3 is on the surface of the β-globin chain, it was thought that polymerization of the abnormal hemoglobin by disulfide linkages might have been responsible for the anomalous behavior on electrophoresis and high performance liquid chromatography. Gel filtration chromatography on G-200 Sephadex confirmed this supposition and demonstrated that the abnormal globin chain polymerized with itself as well as with other globin chains.