British journal of haematology
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The haemoglobin (Hb) patterns of 345 Shiite Saudi Arab cord bloods were examined by alkaline starch-gel electrophoresis. A fast-moving component, identified by structural analysis as Hb Bart's, was found in 52% of cases, the highest incidence of this variant yet recorded. The levels of Hb Bart's ranged from 0.5 to 16% of the total haemoglobin. ⋯ These findings indicate that elevated levels of Hb Bart's in this population are due to the presence of alpha thalassaemia. The absence of hydrops fetalis and the rarity of Hb-H disease despite the intense inbreeding in this population, points to an alpha-thalassaemia genotype that is, in terms of phenotypic expression, intermediate between the heterozygous state for alpha-thalassaemia I and Hb-H disease. A possible molecular basis for this genotype is suggested.