Objective: The 3.7 kb deletion (-α3.7) in the α-globin cluster, which characterizes α+-thalassemia, has been reported to have a carrier rate of 4.78% in southern China. Three -α3.7 subtypes have been identified worldwide. However, the -α3.7 III subtype has not previously been identified in China. Herein, we reported identification of the -α3.7 III subtype in a Chinese patient.
Methods: We used gap-PCR and a liquid chip system to detect α-thalassemia mutations. Multiple ligation-dependent probe amplification was performed to detect the large deletion. We finally used Sanger sequencing and single molecule real-time sequencing to characterize and confirm the genotype.
Results: The proband, characterized as -α3.7 III heterozygous, showed microcytosis and hypochromic red cells, with a mean corpuscular volume of 78 fL and mean corpuscular hemoglobin of 25.4 pg. The proband's mutation was inherited from her father, who had normal blood parameters.
Conclusion: We first identified the -α3.7 III subtype in China. Consequently, all -α3.7 subtypes have now been identified in the Chinese population. Therefore, attention should be paid to -α3.7 III in clinical prenatal diagnosis, given that commonly used methods such as gap-PCR may lead to misdiagnosis or missed diagnosis.
Keywords: -α3.7 III; -α3.7 subtypes; Chinese population; microcytosis and hypochromic red cells; single molecule real time sequencing.