Hemoglobin Bougardirey-Mali β119 (GH2) Gly → Val. An Electrophoretically Silent Variant Migrating in Isoelectrofocusing as Hb F

Abstract

Hemoglobin Bougardirey-Mali was detected by isoelec-trofocusing during a screening in a 32 years old African, a native of Mali.

This abnormal Hb, representing 35% of the total, exhibited the same pI as that of Hb F. In contrast, it was indistinguishable from Hb A in all the electrophoretic systems tested, and equally by its resistance to alkaline denaturation.

Structural studies have shown that the abnormality was localized on the β chain. A fingerprint of the tryptic digest of the aminoethylated β chain indicated the absence of the βT12 b. The presence of an abnormal βT12 b was suspected in the T14-15 spot, as indicated by the intensity of staining and its amino acid composition. βT12 b was isolated by chromatography on PA 35. Its sequential analysis by manual Edman-dansyl degradation showed that glycine 119 was replaced by a valine residue.

This mutation is localized in a α₁β₁ contact, which makes the molecules slightly unstable. The clinical consequences of this mutation seem to be minor; similar observations have been reported for the otksr Hb mutated at the same locusl i.e. Hb Fannin-Lubbock β119 Gly → Asp.