Genetic testing of children with suspected thalassemia in Chongqing area of China: an analysis of 28 287 cases

Abstract:

Objective To investigate the positive rate of thalassemia genes，genotypes，and distribution characteristics in children in Chongqing area of China.Methods Common α- and β-thalassemia gene mutation sites were detected for 28 287 children with suspected thalassemia who underwent hematological screening at Children’s Hospital of Chongqing Medical University from January 2011 to December 2022，and related analyses were performed to investigate the changing trends of detection rate and the composition ratio of thalassemia carriers，as well as genotype distribution.Results Among the 28 287 children with suspected thalassemia，there were 15 249 children with thalassemia，with a positive rate of 53.91%. The positive rates of α-，β-，and αβ-thalassemia were 22.41%（6 340 cases），30.43%（8 609 cases），and 1.06%（301 cases），respectively，and the positive rate of moderate-to-severe thalassemia was 2.47%（698 cases）. From 2011 to 2022，the linear regression k-values of the composition ratio of α-thalassemia carriers in each age group were -0.002，0.004，0.006，0.010，and 0.012，respectively，while those for β-thalassemia were 0.011，0.004，0.002，and -0.001，respectively. A total of 21 α-thalassemia genotypes were detected，among which --SEA/αα was the main genotype accounting for 69.58%. A total of 46 β-thalassemia genotypes were detected，with the main genotypes of CD17/βN，CD41-42/βN，and IVS-II-654/βN，accounting for 31.75%，27.92%，and 25.21%，respectively，and 84.88% in total.Conclusion There is a relatively high positive rate of common thalassemia gene mutation sites in children in Chongqing area，as well as a relatively high proportion of children with moderate-to-severe thalassemia. From 2011 to 2022，the detection rate of α-thalassemia carriers increases with age，while that of β-thalassemia decreased with age，indicating that some β-thalassemia patients receive genetic diagnosis at an older age. In Chongqing area，the main thalassemia genotypes are --SEA/αα，CD17/βN，CD41-42/βN，and IVS-II-654/βN in children，which are consistent with those in adults，but are different from those in the areas with a high incidence rate of thalassemia，such as Guangdong and Guangxi provinces. These results have significant implications for the intervention and prevention of thalassemia in Chongqing area.