Beta-thalassemia in the Korean population.

Beta-thalassemia is uncommon in the Korean population, however it must be considered in the differential diagnosis of hypochromic anemia. The molecular characterization of beta-thalassemia is absolutely necessary for molecular diagnosis as well as any genetic epidemiological study in this region. We analyzed the molecular basis of beta-thalassemia in 47 Korean families. Using direct sequencing of genomic DNA amplified through PCR and haplotype analysis, 44 beta-thalassemia genes were characterized, all of which were heterozygous. Fourteen different mutations were identified. The common mutations noted included the initiation codon (CD) ATG-->AGG (23.4%), CD 17 A-->T (21.2%), and IVS-II-1 G-->A (12.7%). Interestingly, mutations causing dominantly inherited beta-thalassemia were common (17.0%). All cases of IVS-II-1 G-->A mutations were linked to the silent mutation of CD 91 C-->T of the -globin gene. The initiation CD ATG-->AGG and IVS-II-1 G-->A with CD 91 C-->T were found in the Far East only, and may be inherited from a common origin for each mutation, at least in Koreans. CD17 A-->T and CDs 41/42-TTCT were suggested to be introduced by gene-flow from southern China. Otherwise, Hb Korea, CDs 89/90 -GT and a novel beta-thalassemia mutation, CD 131 CAG-->TAG, were only identified in Koreans. This mutation spectrum is characteristic of the low prevalent area of beta-thalassemia, however it is quite different even from the adjacent countries, Japan or China.