Analysis of genotype and phenotype of αβ-thalassemia from Hakka people of Heyuan in Guangdong Province

Objective To investigate the genotype, hematological characteristics and incidence of αβ-thalassemia in Heyuan of Guangdong province. Methods 11 398 cases of patients from Heyuan of Guangdong province were screened by routine blood testing and hemoglobin (Hb) electrophoresis analysis to detect thalassemia. The deletion of α-thalassemia gene was determined by gap-PCR, while the gene mutation of β-thalassemia and α-thalassemia were determined by reverse dot blot (RDB) assay. Results Among 11 398 cases, 250(2%) were identified to be αβ-thalassemia. The most prevalence genotype was --SEA/-αα combined with βCD41-42/βN, --SEA/-αα combined with βIVS-Ⅱ-654/βN, --SEA/-αα combined with β-28/βN, the number of which is 50, 43 and 27, respectively. In addition, there were 11 cases of HbH combined with β-thalassemia. As a whole, Thirty-nine genotypes of α-thalassemia combined with β-thalassemia were detected. There were significant differences between <18 age group and ≥18 age group in MCV and MCH (P=0.002; P=0.004), but there were no significant differences between age groups in Hb levels (P=0.235). In addition, there were significant differences between different genders in Hb levels (P=0.006). Significant differences were found between three different combinations of genotype in MCV and MCH(P=0.000, respectively). Conclusion αβ-thalassemia has relatively high incidence and lacks specific hematological marker for diagnosis. Patients with positive screening result of should be given gene diagnosis of α-thalassemia and β-thalassemia to avoid missed identification and to provide proper genetic counseling and prenatal diagnosis of this disease. Key words: Thalassemia; Gene diagnosis; Genotype; Phenotype