Delta beta thalassemia.

Abstract

A 19-year-old woman of Lebanese ethnic origin was referred for investigation of microcytosis. Her blood count showed: red cell count 5.32 × 1012/L, hemoglobin concentration 116 g/L, mean cell volume 70 fL, mean cell hemoglobin 21.8 pg and mean cell hemoglobin concentration 312 g/L. Her blood film showed microcytosis, mild hypochromia and poikilocytosis. The poikilocytes included elliptocytes (left Image) and small numbers of irregularly contracted cells (right Image). There were only occasional target cells. Thalassemia trait was suspected and high performance liquid chromatography (HPLC) was performed. Hemoglobin A2 was normal at 2.8%, but hemoglobin F, as quantified by the Bio-Rad Variant II instrument (unmodified hemoglobin F), was increased to 11.8%; the total hemoglobin F was about 14% if acetylated F, which is not integrated by the instrument, was included. The likely diagnosis now became δβ thalassemia. This diagnosis was confirmed by Gap-PCR which showed heterozygosity for the Sicilian δβ thalassemia deletion mutation. The diagnosis of δβ thalassemia is important, particularly in a patient in the reproductive age range, since homozygosity or compound heterozygosity with β thalassemia can lead to thalassemia intermedia. It might be expected that the hemoglobin A2 would be reduced since one δ gene has been deleted but in fact it is often normal. Hemoglobin F is usually between 5 and 20%. Nothing to report.