Characterization of HbH Disease Caused by Compound Heterozygotes α+-Thalassemia 3.7 kb Deletion and a Large Novel α0-Thalassemia Deletion.

We characterized here for the first time the deletional HbH disease caused by a large novel α0-thalassemia deletion in a 26-year-old Burmese pregnant woman. Capillary electrophoresis (CE) electropherogram revealed HbA2ABart's H, whereas, a single-tube multiplex real-time PCR with EvaGreen and high-resolution melting (HRM) analysis for diagnosis of three common α0-thalassemia --SEA, --THAI, and --CR deletions showed a negative result. Thus, a multiplex ligation-dependent probe amplification (MLPA) analysis was performed. The α-globin gene cluster deletion was observed spanning from upstream of HBZ to downstream of HBQ1 exon 3 covering three functional genes (HBZ, HBA2, and HBA1). This large novel deletion has not been reported previously thus we named it α0-thalassemia (--BURMESE) due to its origin. In addition, deletional HbH disease is a result of compound heterozygosity for --BURMESE/-α3.7. Therefore, the characterization and identification of --BURMESE is essential for genetic counseling and preventing new cases of HbH disease and Hb Bart's hydrops fetalis.