Thalassemia intermedia due to a novel mutation in the second intervening sequence of the beta-globin gene.

We describe a new beta-thalassemia (thal) mutation in the beta-globin gene of an 8-year-old Moroccan boy. This homozygous mutation produces a phenotype of thalassemia intermedia and is associated with the Mediterranean haplotype IX. We discuss the pathophysiological consequences of this mutation which is located near the 3' end of the second intervening sequence (IVS-II) of the beta-globin gene.