Identification of a novel 10.3 kb deletion causing?0-thalassemia by third-generation sequencing: Pedigree analysis and genetic diagnosis

Background: alpha-thalassemia is an inherited blood disorder caused by variants in the alpha-globin gene cluster. Iden-tification of the pathogenic alpha-globin gene variants is important for the diagnosis and management of thalassemia.Methods: 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).Results: Hematological analysis suggested that proband A had alpha-thalassemia traits, and proband B had HbH disease traits. However, only a-alpha 3.7 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 alpha-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 alpha-thalassemia.Conclusion: A novel alpha-thalassemia deletion was identified for the two families by TGS. Our work broadened the molecular spectrum of alpha-thalassemia, and was beneficial for the diagnosis, genetic counseling and management of alpha-thalassemia.

Automated summary

A novel alpha-thalassemia deletion was identified in two families through TGS, expanding the molecular spectrum of alpha-thalassemia and benefiting its diagnosis, genetic counseling, and management.