[HbD Iran-beta-thalassemia association in a Tunisian family].

A nine-year-old boy from Béjà (North-Western Tunisia) was found to have both HbD Iran and beta-thalassemia. This patient presented with anemia and slight enlargement of the spleen and had a history of acute episodes of hemolysis. Structural studies on this hemoglobin variant used several miniaturized techniques, mainly carboxy-methyl-cellulose chromatography, reverse-phase high performance liquid chromatography and manual peptide sequencing using Chang's technique. The glutamic acid in position 22 on the beta chain was found to be replaced by a glutamine, establishing the diagnosis of HbD Iran. Concomitant presence of a thalassemia trait was suggested by the finding in the index patient of microcytosis, hypochromia and increased HbA2. The family study confirmed this patient's combined heterozygous anomalies, showing the D trait in the father and the beta thalassemia trait in the mother. The same combination was found in the index patient's sister who was, however, free of clinical symptoms. The explanation of this difference in clinical expression was provided by the ADN study which disclosed deletion of an alpha gene in the girl. The resulting alpha chain deficiency counterbalanced the beta chain deficiency.