Abstract
Backgroundα-thalassemia is relatively endemic 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 subpopulationMethodsA cohort of 7644 subjects was selected 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.ResultsWe found that the frequency of α-globin triplication in Guizhou province was 0.772% (59/7644). Genotypically, the αααanti4.2/αα accounted for 0.523% (40/7644), the αααanti3.7/αα for 0.235% (18/7644), and the αααanti3.7/–SEA for 0.013% (1/7644). The αααanti4.2/αα is more prevalent than the αααanti3.7/αα in Guizhou. In addition, the frequency of the HKαα/αα (that by GAP-PCR is like αααanti4.2/-α3.7) was 0.235% (18/7644). 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.ConclusionsThese data will be used to update the Chinese 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.
Highlights
Thalassemia is a hereditary hemoglobin disease caused by defects in the globin genes, including deletions and mutations [1]
When in coinherited with β-globin gene mutation(s), the triplicated α-globin genes play a considerable role in pathophysiology of thalassemia by deteriorating the imbalanced α-globin chain synthesis and affecting the erythroid maturation and survival [7, 8], mild to severe thalassemia is often observed in the affected subjects due to the imbalance of α- and β-globin chains [8,9,10]
The αααanti4.2/αα is more prevalent than the αααanti3.7/αα in Guizhou province (p < 0.05)
Summary
Thalassemia is a hereditary hemoglobin disease caused by defects in the globin genes, including deletions and mutations [1]. While a deletion of one or both α-globin genes leads to α-thalassemia, the α-globin genes triplication (ααα) that caused by homologous recombination. There are two types of triplicated α-globin genes: αααanti3.7 and αααanti4.2 [11, 12]. A type of unusual rearrangement of the α-globin gene cluster, called HKαα (Hong Kong αα) allele, contains both the -α3.7 and αααanti4.2 crossover junctions [14, 15]. The HKαα allele does not really contain three copies of α-globin gene.
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