A child presents with hypochromic microcytic anemia, with normal levels of free erythrocyte protoporphyrin . The most likely diagnosis is

Ref Harrison 19 th ed pg 637-638 The diagnosis of b-thalassemia major is readily made during child- hood on the basis of severe anemia accompanied by the characteris- tic signs of massive ineffective erythropoiesis: hepatosplenomegaly, profound microcytosis, a characteristic blood smear ), and elevated levels of HbF, HbA2 , or both.