A 12 months old girl of Punjabi parents developed a pallor since 3 months of age. One unit of blood transfusion was done at 5 months of age. Now presents with pallor, on examination hepatosplenomegaly. Hematoglobin was 3.8 gin/d1, MCV=68, MCH=19. Peripheral smear showed schistocytes. one marrow examination show erythroid hyperplasia. Diagnosis is -