Molecular Epidemiology and Hematologic Characterization of Thalassemia in Guangdong Province, Southern China

Abstract

Introduction: About 2% of the population in the world are carriers of the thalassemia gene. Thalassemia is highly prevalent in Southern China, and traditional clinical testing methods would cause missed diagnosis of partial static thalassemia. Here, we reviewed and summarized a set of simple and clinically feasible thalassemia detection protocols adopted by the Prenatal Diagnosis and Reproductive Center of our hospital. Methods: From January 1, 2015, to December 31, 2020, 31 512 peripheral blood samples and 3828 prenatal samples were collected in our study. All the peripheral blood samples were performed through thalassemia screening by routine blood tests and hemoglobin electrophoresis and gene detection. The prenatal diagnosis would be implemented for the fetus if the parents were carriers of the same type of thalassemia. Results: A total of 6137 (19.48%) cases were diagnosed as thalassemia, in which 4749 (15.07%) were α-thalassemia, 1196 (3.80%) were β-thalassemia and 192 (0.61%) were co-inheritance of α- and β-thalassemia. For prenatal samples, 3160 (82.55%) cases were diagnosed as thalassemia, in which 2021 (52.80%) were α-thalassemia, 997 (26.05%) were β-thalassemia and 142 (3.71%) were co-inheritance of α- and β-thalassemia. In addition, we also found five novel mutations, including NC_000016.9:g.223681-227492del3812; HBA1: c.301-31_301-24delCTCGGCCCinsG; HBA2: c.95+7C>T for α-thalassemia and HBB: c.263_276delCACTGAGTGAGCTG; HBB: c.315+143G>A for β-thalassemia. Conclusion: The present study updates the epidemiological characteristics and mutation spectrum of thalassemia in Southern China and demonstrated five novel mutations. Our research provides a reference for clinical diagnosis and treatment, prenatal diagnosis, or reproductive genetic counseling for patients with thalassemia in Guangdong.

Keywords: gene detection; prenatal diagnosis; rare type; screening; thalassemia.

Figure 1.

The prevalence of peripheral blood and prenatal samples and the composition ratio of different thalassemia. A and E represent the prevalence of thalassemia in the peripheral blood samples and prenatal samples, respectively; B, C, D respectively represent the proportion of different clinical phenotypes in each type of thalassemia in postnatal samples; F, G, H respectively represent the proportion of different clinical phenotypes in each type of thalassemia in prenatal samples. #TS: Thalassemia silent; TT: Thalassemia trait; TI: Thalassemia Intermedia; TM: Thalassemia Major.

Figure 2.

Sanger sequencing verification results of 5 novel mutations. A: NC_000016.9:g.223681-227492del3812; B: HBA1:c.301-31_301-24delCTCGGCCCinsG; C: HBA2:c.95+7C>T; D: HBB: c.315+143G>A; E: HBB:c.263_276delCACTGAGTGAGCTG. The arrows indicate breakpoints/mutation position.