[Prevalence and molecular analysis of α-thalassemia in preschool children in Chongqing city].

OBJECTIVE: To investigate the incidence and the gene mutation frequencies and patterns of α-thalassemia in preschool children in Chongqing city. METHODS: Cluster random sampling was used. A total of 1057 preschool children in three areas of Chongqing were screened by using routine blood test and hemoglobin electrophoresis analysis. Molecular analysis carried out for all the samples. RESULTS: Of the 1057 samples, 55 cases were diagnosed as being carriers of α-thalassemia, which included 80 allele genes. Therefore, the frequency of α-thalassemia carriers in Chongqing was 5.20%. Of the 55 α-thalassemia carriers, five different deletions of α-thalassemia were identified, the three most common deletion types and proportions were 54.55% for the -α(3.7) deletion, 18.18% for --(SEA) deletion, and 9.08% for the -α(4.2) deletion, respectively; eight types of nondeletion defects were determined, containing one case of Hb Quong Sze and seven novel mutations of a-globin gene. Furthermore, 24 cases of α-Triplication were detected with the α-Triplication carrier rate of 2.55%. In addition, in this study we also found two cases of abnormal hemoglobin disorders occurred on α-globin gene, Hb J-Wenchang-Wuming and Hb Arya. Hb Arya was characterized in the Chinese population for the first time confirmed by literature retrieval. CONCLUSION: In this study, we have clarified the carrier frequency and molecular spectrum of α-thalassemia in Chongqing, and we first reported the carrier incidence of α-Triplication in Chongqing. The materials obtained from this study would be of valuable reference for genetic counseling and the examination instruction of children in this area.