Abstract: Objective To investigate the clinical diagnosis of thalassemia intermediate caused by β-thalassemia with α-globin gene triplication. Methods The clinical manifestations of two β-thalassemia heterozygotes were retrospectively analyzed, and the results of β-globin gene sequencing and α-globin gene triplication detection in peripheral blood were also analyzed. Results Case one is a 4 years old girl, and the routine thalassemia gene detection revealed that she was a βCD 41 - 42 heterozygote. Case two was a 13 years old boy, he was a βCD 17 heterozygote detected by routine thalassemia gene sequencing. The clinical manifestations of both cases were moderate to severe anemia with hepatosplenomegaly. No rare mutation was found in β-globin by sequencing. Triplication αααanti4 . 2 fragment was found in case one by Gap-PCR using specific primers. The αααanti3 . 7 fragment was positive in case two by qPCR relative quantification. Conclusion When the result of routine detection indicated beta heterozygote, but with moderate to severe anemia, if there is no rare mutation found by sequencing, the existence of α-globin gene triplication should be considered.

Key words: β-thalassemia; α-globin gene triplication; thalassemia intermedia; αααanti3 . 7 ; αααanti4 . 2