Beta-thalassemia intermedia due to two novel mutations in the promoter region of the beta-globin gene.

Two novel beta-thalassemia mutations affecting the promoter region of the beta-globin gene are described. The first mutation, found in a Moroccan family, is a G-->A substitution at position -190 relative to the beta-globin gene Cap site. The second, found in an Algerian patient, is a G-->C substitution at position -56 relative to the beta-globin Cap site. These two mutations occur in a region (-50 to -300) where promoter elements important for differential control of gene expression have been described and lead to beta-thalassemia intermedia in association with a beta(0)-thalassemia mutations.