Molecular identification of Sicilian (δβ)°-thalassemia associated with β-thalassemia and hemoglobin S in Brazil

Abstract

We describe the clinical and molecular characteristics of two unrelated Brazilian families with an association of the Sicilian form of (δβ)°-thalassemia with hemoglobin S and β-thalassemia. Direct sequencing of the β-globin gene showed only the hemoglobin S mutation in patient 1 and the β-thalassemia IVS1-110 in patient 2. The other allele was deleted in both patients and PCR of DNA samples of the breakpoint region of both patients showed a band of approximately 1,150 bp, expected to be observed in the DNA of carriers of Sicilian (δβ)°-thalassemia. The nucleotide sequence of this fragment confirmed the Sicilian deletion. There are few reports concerning the Hb S/(δβ)°-thalassemia association and patient 2 is the first reported case of Sicilian type of (δβ)°-thalassemia in association with β-thalassemia documented at the molecular level.