GSTM1 and thalassemia: Mothers’ knowledge regarding thalassemia it was adapted from10 and was modified by the investigator to meet the aim of the study including definition, sign and symptoms, management, complications, prevention of disease, prevention of complications, knowledge about blood transfusion (Hb level which determine the need for blood transfusion, importance, complications, causes of complications, precaution to avoid complications), nutrition of child with thalassemia, and physical activity of child with thalassemia.