[Thalassemia Genotypes and HbA2 levels of Children in Wuzhou, Guangxi].

Objective: To analyze thalassemia genotypes and distribution of children in Wuzhou Guangxi, and evaluate the diagnostic value of HbA2 in children's thalassemia screening, so as to provide scientific evidence for the prevention and control strategies of thalassemia.

Methods: Four hundred and fifty-eight children suspected with thalassemia in Wuzhou were enrolled from March 2017 to June 2022. The level of HbA2 was detected using Bio-Rad VARIANT II Hb analysis system. The deletion of α-thalassemia was measured with gap-PCR assay, and the point mutation of α- and β-thalassemia was tested with DNA reverse dot blot hybridization assay. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of HbA2 for children's thalassemia.

Results: A total of 304 thalassemia carriers were detected in 458 children, accounting for 66.38%. One hundred and seventy-five cases were defined to be α-thalassemia, with the main type of --^SEA/αα (54.86%). Thirty-six cases were defined to be intermediate α-thalassemia, with the main type of -α^3.7/--^SEA (9.72%). In 108 cases with β-thalassemia, β^CD41-42/β^N was the main type, accounting for 49.07%, followed by β^IVS-Ⅱ-654 /β^N (14.81%). Seven cases were moderate/severe β-thalassemia (predominantly β^-28/β^-28 and β^CD41-42/β^CD17/). Twenty-one genotypes of α- and β-thalassemia were found in the children. There was significant difference of HbA2 level between the children with different types of thalassemia and healthy controls (all P < 0.001). ROC curve analysis showed that the sensitivities of HbA2 for α-thalassemia, β-thalassemia and αβ-thalassemia were 74.3%, 82.4% and 85.7%, with the optimal cut-off values of 2.60%, 3.60% and 3.70%, respectively, the specificities were 64.3%, 96.1% and 96.8%, and the area under the curve were 0.690, 0.887 and 0.916, respectively.

Conclusion: The thalassemia genotypes of children in Wuzhou are diverse. It is necessary to further strengthen the prevention and control measure of thalassemia to reduce birth defects and improve birth quality.