evaluation of hydroxyurea in treatment of b-thalassemia and xmn-1polymorphism and ivsii-1 mutation

background: many efforts have been undertaken until now to find an alternative approach to packed red cell tranfusion in major β-thalassemia. augmentation of fetal hemoglobin by hydroxyurea has proved to be less effective in this condition as compared to sickle cell anemia, probably due to molecular heterogeneity of the former disease. hydroxyurea efficacy and its relation to xmn1 polymorphism and ivsii-1 mutation in major β-thalassemia, was evaluated in this study. patients and methods: in 45 patients (36 with major β-thalassemia and 9 with intermediate β-thalassemia), hydroxyurea, 20mg/kg/day, 4 days a wwek was prescribed. the aim was to stabilize or increase pretransfusion hb at 10.0 g/dl (in each groups) and /or to decrease or discontinue transfusion (in patients with major β-thalassemia). hydroxyurea was administered for at least 6 month and discontinued if there was no response. screening for xmn-1 polymorphism and ivsii-1 mutation was done in most patients.  results: in group a, 25 patients became independent of transfusion and in one patients the need for transfusion was decreased. mean hb in this group increased from 9.8±1.0 g/dl to 10.2±1.3 g/dl (after treatment with hydroxyurea) and serum ferritin decreased from 1844 ng/ml to 867.7 (p=0.006). in group b, elevation of hb from 9.3±1 g/dl to 10.2±1.3g/dl was seen (p=0.000), but there was no significant change in ferritin level (p=ns). the largest elevation in hb level was seen in patients with xmn-1 (+/+), (ivsii-1/ ivsii-1) and (ivsii-1/ other).  conclusion: molecular determination of genetic markers specially xzmn-1 poly,orphism would help to identify candidate for pharmacologic hbf switching by hydroxyurea.