A novel rearrangement of the α-globin gene cluster containing both the -α and αααα crossover junctions in a Chinese family.

BACKGROUND

Thalassemia is one of the most common hemoglobinopathies. Thalassemia is mainly caused by the loss and/or deficiency of one or more globin chains in hemoglobin. The copy number variant (CNV) of α-globin gene is one of the important factors affecting the clinical phenotype of β-thalassemia. The precise detection for this type of variation is needed.

METHODS

Peripheral blood of a 33-year-old man and his family members were collected. Complete blood counts and serum iron levels were measured for participants. Genomic DNA was extracted from all family members. Routine genetic analysis of thalassemia was performed to determine the genotype. Additional PCR-electrophoresis and Multiplex ligation dependent probe amplification (MLPA) were conducted. Single-molecule real-time technology(SMRT) was then performed as a validation assay and further characterization of the variant for family members.

RESULTS

PCR-electrophoresis and MLPA found a new variant, but the exact genotype could not be determined. At last, SMRT identified the new variant as a rearrangement of the α-globin gene cluster named αHKαα (NC_000016.9:g.169818_174075dup169818_174075dup173302_177105del), which contained both the -α and αααα crossover junctions. Carriers of the novel CNV show normal clinical phenotype according to the hematological results.

CONCLUSION

We have identified an unreported CNV (αHKαα) in α-globin gene cluster. The novel CNV not only demonstrates the accuracy and efficiency of our combining strategy in detecting unknown CNVs, but also enriched the variant spectrum of thalassemia.