heterozygous beta thalassemia traitbeta thalassemia trait diagnosisbeta thalassemia trait meansbeta thalassemia trait carrierbeta thalassemia trait anemiabeta thalassemia minor traitdelta beta thalassemia traitsickle beta thalassemia traitbeta traitthalassemia beta trait adalahbeta thalassaemia trait symptomssickle cell trait beta thalassemia