Frequency and clinical significance of erythrocyte genetic abnormalities in Omanis

The frequencies of four malaria associated erythrocyte genetic abnormalities have been established in 1000 Omani subjects. They are: homozygous α⁺ thalassaemia (-α/-α) 0.45; high Hb A₂ β thalassaemia trait 0.015; sickle trait (Hb A/S) 0.061; and glucose 6 phosphate dehydrogenase deficiency (Gd^-): males 0.27, females 0.11. From our data the α⁺ (-α/) thal gene (confirmed by Southern blotting) is pandemic in this population. Moreover, in spite of the very high frequency of Gd^-, oxidative haemolytic syndromes are very uncommon. Also preliminary data indicate that among the Omani population with sickle cell disease, homozygosity of the α⁺ gene markedly modifies the clinical picture.