We studied the presence of the XmnI site and the ␤-globin haplotype in 24 individuals, carriers of the IVSII-1 G→A ␤ 0 -globin mutation, of whom fourteen had no detectable levels of HbF, while ten coming from 5 families, presented HbF levels ranging from 1.7 to 9% of the total Hb. Of these ␤-thalassaemia heterozygotes with fetal hemoglobin, 6 were females and 4 were males with median HbF levels of 4.85% and 4% respectively, and an excess of G

We studied the presence of the XmnI site and the ␤-globin haplotype in 24 individuals, carriers of the IVSII-1 G→A ␤ 0 -globin mutation, of whom fourteen had no detectable levels of HbF, while ten coming from 5 families, presented HbF levels ranging from 1.7 to 9% of the total Hb. Of these ␤-thalassaemia heterozygotes with fetal hemoglobin, 6 were females and 4 were males with median HbF levels of 4.85% and 4% respectively, and an excess of G