Mild Thalassemia Intermedia Due to Interaction of δβ-Thalassemia with Triplicated α-Globin Genes.

Here we report a Spanish family in which two members, mother and daughter, present with a phenotype of mild non transfusion-dependent thalassemia (NTDT) due to compound heterozygosity for δβ-thalassemia (δβ-thal) and the α gene triplication ααα-3.7. They carry the most prevalent form of δβ-thal in Spain, the so-called Spanish δβ0-thal, which consists of a deletion of 114 kb that affects the δ and β genes. A mild microcytic anemia [hemoglobin (Hb) 10.6 g/dL and mean corpuscular volume (MCV) 72.8 fL, and Hb 10.9 g/dL and MCV 70.0 fL, respectively], hypocromia [mean corpuscular Hb (MCH), 23.4 and 22.6 pg, respectively], increased red blood cell (RBC) distribution width (RDW) (20.0 and 21.9%, respectively), high fetal Hb (Hb F) (23.7 and 21.6%, respectively) with Hb A2 within the normal range, and splenomegaly, were present in the affected subjects. In areas were δβ-thal is prevalent, the interaction with triplicated α-globin genes should be suspected in cases of mild NTDT if Hb F is high and Hb A2 is not increased.