[Ethnic differences in genotype distribution of thalassemia between Han and Li populations in southern Hainan]

To analyze the ethnic differences in the genotype distribution of thalassemia between the Han and Li ethnic groups in the Qiongnan region (southern Hainan). A cross-sectional study employing a stratified multistage sampling method was conducted from January 2019 to December 2023. A total of 4 493 high-risk individuals (2 734 Han and 1 759 Li) from southern Hainan (including Sanya, Ledong, Baoting, Lingshui, and other counties) underwent thalassemia genetic testing. The genotype distribution was statistically analyzed. Inter-group comparisons were performed using χ² test or Fisher's exact test. The results showed an overall thalassemia positivity rate of 66.70% (2 997/4 493), with carrier, intermediate and major thalassemia rates of 62.01% (2 786/4 493), 3.98% (179/4 493) and 0.71% (32/4 493), respectively. The positivity rates for thalassemia were 87.83% (1 545/1 759) in the Li ethnic group and 53.11% (1 452/2 734) in the Han ethnic group. Among them, the Li ethnic group exhibited significantly higher positivity rates for α-thalassemia (71.12% vs. 40.64%, χ²=398.90, P<0.001) and α/β-compound thalassemia (13.36% vs. 3.33%, χ²=160.06, P<0.001) compared to the Han ethnic group, whereas the Han ethnic group had a higher β-thalassemia rate (9.14% vs. 3.35%, χ²=56.03, P<0.001). Both ethnic groups shared common α-thalassemia alleles (-α^3.7 and -α^4.2), but the --^SEA allele proportion was significantly higher in Han (21.33% vs. 4.34%, χ²=231.45, P<0.001). Six rare -α^21.9 mutations (0.26%) were exclusively identified in the Li ethnic group, whereas none were found in Han. For β-thalassemia, the β^CD41-42 allele was predominant in Li (96.60% vs. 71.01%, χ²=77.24, P<0.001), whereas other alleles (β^IVS-II-654, β^CD71-72, β^CD17, and β^-28) were more prevalent in Han (11.01%, 6.96%, 4.64%, and 3.19% vs. 1.54%, 0.00%, 0.31%, and 0.62%, respectively),all P<0.05. In conclusion, distinct ethnic disparities in thalassemia genotype distribution are observed in southern Hainan. The Li ethnic group is predominantly characterized by α-thalassemia and α/β-compound genotypes with a predominant β^CD41-42 mutation. In contrast, the Han ethnic group displays higher --^SEA proportion and heterogeneous β-thalassemia genotypes.