Abstract: Objective：To examine clinical characteristics of heterozygote and double heterozygote of three rare mutations [Hb Constants Spring（Hb CS），Hb Westmead（Hb WS） and Hb Quong Sze（Hb QS）] among alpha-thalassemia patients in Guangxi province, China. Methods：135 alpha-thalassemia patients, and 40 controls, were included in this study. Routine examination of blood and hemoglobin electrophoresis were performed. The alpha-thalassemia mutations were detected using Gap-PCR and reverse dot-blotting. Results：There were no clinical symptoms in three heterozygote groups and the double heterozygote group of αCSα/αWSα. MCV and MCH in the heterozygote group of Hb QS were significantly lower than those in other heterozygote groups（Hb CS and Hb WS）（P＜0.05）. However，there was mild clinical symptoms in the double heterozygote group of αCSα/αQSα, while MCV and MCH were also significantly lower than those in other heterozygote groups（Hb CS and Hb WS）（P＜0.05）. Conclusions： The heterozygote Hb CS，heterozygote Hb WS and double heterozygote αCSα/αWSα are the silent carrier in clinical manifestations, the heterozygote Hb QS is the thalassemia trait, and the double heterozygote αCSα/αQSα is similar to the HbH disease. It is important to note this variability of clinical manifestations of those double heterozygotes in genetic consultation.

Key words: Alpha-Thalassemia, Point mutation, Genotype, Heterozygote