Hb O-TIBESTI [β121(GH4)Glu → Lys; β11(A8)Val → Ile], A HEMOGLOBIN VARIANT CARRYING IN THE SAME β CHAIN THE SUBSTITUTIONS OF Hb O-ARAB AND Hb HAMILTON, FOUND IN COMBINATION WITH Hb S [β6(A3)Glu → Val]

Hb O-Tibesti, carries in the same chain the substitution of Hb O-Arab [β121(GH4)Glu → Lys] and that of Hb Hamilton [β11(A8)Val → Ile]. Hb O-Tibesti may be distinguished from Hb O-Arab by polyacrylamide gel electrophoresis in the presence of urea and Triton-X100, and by reversed phase high performance liquid chromatography. It was found in a compound heterozygous condition with Hb S [β6(A3)Glu → Val] in a child of Chad-Sudanese descent, suffering from a sickle cell syndrome. Compared to the classical description of the Hb S Hb O-Arab association, the additional Hb Hamilton mutation does not seem to modify the clinical presentation.