We report in this paper a novel thalassemia mutation (insertion of a single A nucleotide within the exon 1, at codon 18, of the beta-globin gene) associated with a deletion of the deltabeta-globin gene region, in a patient exhibiting high persistence of fetal hemoglobin. The novel mutation causes a frameshift with the generation of a UGA stop codon. Analysis of the parent's DNA demonstrates that the A insertion and frameshift mutation are inherited from the father, while the deltabeta-globin gene deletion is inherited from the mother. Gene dosage analysis and deletion-specific PCR demonstrate that the deletion is the (deltabeta)(0) Sicilian deletion, involving a 13.4-kb deltabeta-globin gene region.