Co-Inheritance of Beta & Delta-Globin Gene (HbYialousa) Mutations in an Iranian <i>β</i>-Thalassemia Carrier

Abstract

Introduction: Beta-thalassemia is characterized by absence or reduced synthesis of the β -globin. Carriers of β -thalas - semia, typically have microcytic hypochromic anemia and elevated hemoglobin HbA 2 and normal HbF level. On the other hand carriers of severe alpha-thalassemia also have similar CBC parameters to that of β -thalassemia with normal HbA 2 level. Co-presence of mutations in the β -globin and delta-globin genes (point mutations or deletions) usually give normal HbA 2 and elevated HbF level. We report a β -thal carrier with normal level of HbA 2 and increased level of HbF who had a point mutation in CD39 on the beta-globin gene and a point mutation in CD27 on the δ -globin gene named Hb-Yialousa. Materials & Methods: An individual with low hematological indices, normal HbA 2 and elevated HbF was referred to our center as routine premarital screening program. Mutations in the β -globin and δ -globin genes were screened using ARMS and sequencing methods. Results: The mutation in β - and δ - globin genes were identified as CD39 and CD27 (HbYialousa) respectively. No point mutation or deletion in α -globin gene was identified. Discussion : We showed that normal HBA 2 with elevated HbF level is due to co-inheritance of delta-globin gene mutation with mutation in the β -globin gene. When screening for β -thalassemia, one has to either rule out presence of α -globin gene mutation of mutation in the delta-globin gene.