Online edition:ISSN 2758-089X


Relation Between Polycythemia and Function of Hemoglobin with Amino Acid Substitution in α1β2 Contact Hb Chesapeake [α92 (FG4) Arg→Leu ]and Hb J Cape Town [α92 (FG 4) Arg→Gln]

Two variants of abnormal hemoglobins with increased oxygen affinity, Hb Chesapeake (α92 Arg→Leu) and Hb J Cape Town (α92 Arg →Gln), were detected by isoelectric focusing during a population survey of residents of Aichi Prefecture. This was the first time for these abnormal hemoglobins to be found in Japanese. Following this discovery, a comparative study of the two variants was carried out employing isoelectric focusing, structural analysis (fingerprinting and amino acid analysis), functional analysis (oxygen equilibrium), dissociation into dimers, autoxidation, biosynthesis, and plasma erythropoietin level measurement. The carriers of Hb Chesapeake, who were heterozygous for the abnormal hemoglobin, showed mild polycythemia. Those of Hb J Cape Town, however, were free of polycythemia, although their hematological values (RBC, Ht and Hb) were close to the upper limits of the normal ranges. The results of the present study support the view that increased production of erythropoietin due to a tissue oxygen deficiency is not the only decisive factor for causation of polycythemia in variant hemoglobins with high oxygen affinity.

Mori H