Molecular Spectrum, Ethnic and Geographical Distribution of Thalassemia in the Southern Area of Hainan, China

BackgroundThalassemia is one of the most common genetic diseases in southern China. Accurate population frequency data regarding the occurrence and distribution of thalassemia are important for designing appropriate prevention strategies for thalassemia. This study aims to reveal the molecular spectrum, ethnic and geographical distribution of thalassemia in the southern area of Hainan Province, China. MethodsA total of 9813 suspected carriers of thalassemia were screened for genetic analysis by using the PCR-reverse dot blot hybridization method targeting three known deletions of alpha-thalassemias (--(SEA), -alpha(3.7), and -alpha(4.2)), three nondeletional mutations of alpha-thalassaemias (alpha(CS), alpha(QS), and alpha(WS)) and the 17 most common mutations of beta-thalassaemias in the Chinese population. ResultsApproximately 6,924 subjects were genetically diagnosed as thalassemia carriers or patients, including 5812 cases of alpha-thalassemia (83.9%), 369 cases of beta-thalassemia (5.3%), and 743 cases of alpha-composite beta-thalassemia (10.7%). A total of 21 distinct genotypes were identified among the 5,812 alpha-thalassemia carriers, -alpha(4.2)/alpha alpha, -alpha(3.7)/alpha alpha, and -alpha(3.7)/-alpha(4.2) were the most common alpha-thalassemia genotypes. The most frequent beta-thalassemia genotype was beta(CD41-42)/beta(N), with a notable proportion of 69.6%, followed by the beta(-28M)/beta(N), beta(IVS-II-654)/beta(N), beta(CD71-72)/beta(N), beta(E)/beta(N), and beta(CD17)/beta(N) genotypes. In addition, 37 genotypes were detected among the 743 cases of both alpha- and beta-thalassemia mutations. The alpha-thalassemia genotypes were most commonly found in the Li people, who accounted for 73.5% of alpha-thalassemia carriers. The beta-thalassemia genotypes were most commonly identified in the Han people, who accounted for 59.4% of beta-thalassemia carriers. Among the subjects carrying both alpha- and beta-thalassemia variations, only three ethnic minorities were identified, including the Li, Han, and Miao people, accounting for 82.0, 17.4, and 0.7%, respectively. ConclusionsOur study indicates that there is high genetic heterogeneity, geographical and ethnic differences in thalassemia in populations in the southern area of Hainan Province. These findings will be helpful in guiding genetic counseling and prenatal diagnosis of thalassemia in Hainan Province.