Molecular Basis of Hemoglobin-HDisease in the

was restriction endonuclease mapping of the found in 3, and a “dysfunctional” gene in DNA in the Mediterranean populations. Of one. We conclude that the predominant the 1 2 patients studied from Cyprus and cause of a-thalassemia in these populaSardinia, 8 had the typical deletion defect tions is gene deletion. T HE HUMAN a-GLOBIN GENE loci are duplicated’� and the two loci are tightly linked5’6 on chromosome l6.� In a diploid cell, the normal genotype for ct-globin can be represented as act/aa. Recent studies have demonstrated that in both the Asian and the black populations, gene deletion is the common cause of a-thalassemia.8� The clinical states ofct-thalassemia are in a large part explained by the two genotypes observed: the ct-thalassemia-2 gene, due to deletion of a single locus (-a); and the ct-thalassemia-l gene with deletion of both loci (- -). In