Two new variants with the same substitution at position beta 122: Hb Bushey [beta 122(GH5)Phe -> Leu] and Hb Casablanca [beta 65(E9)Lys -> Met;beta 122(GH5)Phe -> Leu]

Hb Bushey, found in a Chinese baby and his father, is a new variant with a point mutation leading to the substitution Phe-->Leu at position beta 122, Hb Casablanca, found in a family from Morocco, is a further example of a he moglobin variant that carries two abnormalities in the same chain; the firs t is identical to that of Hb Bushey and the second to that of Hb J-Antakya [beta 65 (E9)Lys-->Met]. Structural abnormalities of both Hbs were determin ed by protein chemistry methods including electrospray and tandem mass spec trometry. Their stability and oxygen binding properties were found to be id entical to those of Db A. Various mechanisms that may lead to two point mut ations in the same chain are reviewed briefly.