Increased prevalence of thalassemia in young people in Korea: Impact of increasing immigration

Background: Thalassemia is highly prevalent in Southeast Asia but is rare in Korea; however, Southeast Asian immigrant population is recently rising in Korea. We investigated the prevalence of thalassemia in Korea in the context of increasing immigration. Methods: This prospective, observational, multicenter study was conducted between September 2015 and August 2017. A total of 669 subjects <30 years living in Korea were grouped into the multiethnic (N=314) and Korean (N=355) groups. Hb electrophoresis and complete blood count (CBC) were performed. If low mean corpuscular volume with high red blood cell distribution width coefficient of variation or a high fetal Hb (HbF) or Hb alpha 2 (HbA2) level was observed, genetic testing of the α- and β-globin genes was performed. In addition, the number of potential thalassemia carriers in Korea was estimated by multiplying the prevalence of thalassemia in a specific ethnicity by the number of immigrants of that ethnicity. Results: Twenty-six multiethnic and 10 Korean subjects showed abnormal results for Hb electrophoresis and CBC. Eighteen multiethnic subjects and four Korean subjects were tested for α-globin and β-globin gene mutations. Within the multiethnic group, five subjects (1.5%) were α-thalassemia carriers, and six (1.9%) were β-thalassemia minor. The SEA deletion in HBA1 and HBA2, and c. 126-129delCTTT (p. Phe42Leufs^∗19) mutation of HBB were the dominant inherited mutations. Conclusions: The prevalence of thalassemia in young people in Korea is increasing due to the increasing number of Southeast Asian immigrants.