Abstract
To examine the thalassemia genotypes and distribution among pregnant women in Shenzhen, as well as the diagnostic value of HbA2 in thalassemia screening, in order to provide scientific evidence for thalassemia prevention and control in this region. From January 2018 to June 2024, Shenzhen recorded 3243 cases of suspected thalassemia carriers. HbA2 was detected by hemoglobin electrophoresis analysis. The deletions of α-thalassemia mutation by gap-polymerase chain reaction (gap-PCR), and the non-deletion α-thalassemia mutations and β-thalassemia mutations were detected by reverse dot-blot hybridization (RDB-PCR). The receiver operating characteristic curve (ROC) was utilized to analyze the diagnostic value of HbA2 for pregnant women's thalassemia. A total of 656 carriers were detected in 3243 pregnant women with suspected thalassemia carriers, with a positive detection rate of about 20.22%. 459 cases were defined to be α-thalassemia, with the main type of (--)(SEA)/αα (47.71%). 170 cases were defined to be β-thalassemia, with the main type of β(CD41-42)/β(N) (31.76%). 27 genotypes of αβ-thalassemia were noted in pregnant women. There was significant difference of HbA2 level between the pregnant women 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 89.7%, 96.5% and 96.2%, with the optimal cut-off values of 2.71%, 3.71% and 3.86%, respectively, the specificities were 26.6%, 98.5% and 94.5%, and the area under the curve were 0.587, 0.979 and 0.972, respectively. The thalassemia genotypes of pregnant women in Shenzhen are diverse. It is necessary to strengthen the prevention and control measure of thalassemia in order to reduce birth defects and improve birth quality.