Identification of a novel 10.3 kb deletion causing α0-thalassemia by third-generation sequencing: Pedigree analysis and genetic diagnosis

α-thalassemia is an inherited blood disorder caused by variants in the α-globin gene cluster. Identification of the pathogenic α-globin gene variants is important for the diagnosis and management of thalassemia.Two suspected families from Xiantao, Hubei Province were recruited in this study. The family members underwent hemoglobin testing. Polymerase Chain Reaction based reverse dot blot (PCR-RDB) was employed to identify the known variants. Next-generation sequencing (NGS) and third-generation sequencing (TGS) were performed to screen the potential disease-causing variants, which were validated by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA).Hematological analysis suggested that proband A had α-thalassemia traits, and proband B had HbH disease traits. However, only a -α3.7 mutation had been detected by PCR-RDB and NGS in the proband of family B. Subsequent TGS identified a novel 10.3 kb deletion (NC_000016.10:g.172342-182690del) covering the HBA1, HBQ1 and HBA2 genes in the α-globin gene cluster in both family A and B, which was confirmed by Sanger sequencing and MLPA. These results indicated that the novel deletion is likely responsible for α-thalassemia.A novel α-thalassemia deletion was identified for the two families by TGS. Our work broadened the molecular spectrum of α-thalassemia, and was beneficial for the diagnosis, genetic counseling and management of α-thalassemia.