Treatment with hydroxyurea in a patient compound heterozygote for a high oxygen affinity hemoglobin and β-thalassemia minor

Compound heterozygotes for beta-thalassemia and high oxygen affinity hemoglobin (Hb) have been documented, but experience in the management of such rare cases is minimal. Although hydroxyurea (HU) has never been used in a heterozygote with high oxygen affinity Hb and beta-thalassemia, we hypothesized that it would decrease erythrocytosis through a lowered production of abnormal cells and increase of P-50 by induction of fetal hemoglobin (HbF). We present the case of a patient with compound high oxygen affinity Hb mutation with beta-thalassemia. PCR analysis revealed combined Hb Regina and IVSI-110 G/A mutations. Treatment with HU caused a decrease in Ht (61.1% to 38.6%) and erythrocyte volume (74.87 mL/kg to 40.65 mL/kg), as well as an increase in P-50 (6 mmHg to 10 mmHg) and HbF level (3.6% to 29.8%) at 12-month follow-up. Effects of HU on 2,3 DPG and HbNO levels did not appear to be predictable. Corroboration with other cases is needed to establish solid evidence on the clinical efficacy of HU in this population.