Prevalence and Clinical Phenotype of the Triplicated α-Globin Genes and its Ethnic and Geographical Distribution in Guizhou of China

Abstract Background: Thalassemia is relatively epidemic in Guizhou province of southwestern China. To predict the clinical manifestations of α-globin gene aberration for genetic counseling, we examined the prevalence of the α-globin triplication and the genotype-phenotype correlation in this subpopulationMethods: A cohort of 7644 subjects was collected from nine ethnicities covering four regions in Guizhou province of China. Peripheral blood was collected from each participant for routine blood testing and hemoglobin electrophoresis. PCR-DNA sequencing and Gap-PCR were used to identify the thalassemia gene mutations. Chi-square tests and one-way analysis of variance (ANOVA) were used to statistically analyze the data. Results: We found that the frequency of α-globin triplication in Guizhou province was 0.759% (58/7644). Genotypically, the αααanti4.2/αα accounted for 0.523% (40/7644), the αααanti3.7/αα for 0.235% (18/7644). The αααanti4.2/αα is more prevalent than the αααanti3.7/αα in Guizhou. In addition, the frequency of the αααanti4.2/-α3.7 (HK αα) was 0.235% (18/7644), and the αααanti3.7/--SEA was 0.013% (1/7644). Ethnically, the Tujia group presented the highest prevalence (2.47%) of α-globin triplication. Geographically, the highest frequency of the α-globin triplication was identified in Qiannan region (2.23%). Of the triplicated α-globin cases, 5 coinherited with heterozygote β-thalassemia and presented various clinical manifestations of anemia. Conclusions: These data will be used to update the triplicated α-globin thalassemia database and provide insights into the pathogenesis of thalassemia. These findings will be helpful for the diagnosis of thalassemia and future genetic counseling in those regions.