Two new Variants with the Same Substitution at Position β122: Hb Bushey [β122(GHS)Phe→Leu] and Hb Casablanca [β65(E9)Lys→Met;β122(GHS)Phe→Leu]

Abstract

Hb Bushey, found in a Chinese baby and his father, is a new variant with a point mutation leading to the substitution Phe→tLeu at position β122. Hb Casablanca, found in a family from Morocco, is a further example of a hemoglobin variant that carries two abnormalities in the same chain; the first is identical to that of Hb Bushey and the second to that of Hb J-Antakya [β65 (E9)Lys→Met]. Structural abnormalities of both Hbs were determined by protein chemistry methods including electrospray and tandem mass spectrometry. Their stability and oxygen binding properties were found to be identical to those of Hb A. Various mechanisms that may lead to two point mutations in the same chain are reviewed briefly.