Distribution of α1 Immunoglobulin Gene 3' Enhancer hs1,2 Polymorphisms in Chinese and Its Comparison with Caucasians

[Objectives] To investigate the distribution of the polymorphisms in the 3' enhancer hs1,2 region of the al immunoglobulin gene in the Chinese population and its comparison with Caucasians. [Methods] Genomic DNA was extracted form 201 healthy Chinese Han subjects. The sizes of the variable numbers of tandem repeats (VNTR) located in the 3' enhancer hs1,2 region of the al immunoglobulin gene were determined by polymerase chain reaction (PCR) and gel electrophoresis, and confirmed by DNA sequencing. [Results] Three different allele sizes of the VNTR were identified in our subjects. They were assigned as α1A,α1B, and α1C, respectively (represent one, two, and three repeal sequences respectively), with the alleles frequencies of 30.3%, 59.7%, and 10.0%, respectively. Six different genotypes were comprised from the three alleles with the frequencies of 12.0%, 32.3%, 37.8%, 4.5%, 11.4%, and 2.0% for AA, AB, BB, AC, BC, and CC genotypes, respectively. Comparing with the reported Caucasoid population the C allele and the BC, CC, AC genotype frequencies were significantly higher (x2=73.77, P0.001); the A allele and the AB genotype frequencies were significantly lower (x2=72.85, P0.001). [Conclusion] The allele and genotype frequencies of Iα1 hs1,2 gene in the Chinese Han population were significantly different from the Caucasians with a higher C allele frequency and BC, AC genotypes, and lower A allele frequency and AB genotype. The results may have implications in the explanations of the different incidences of some IgA-related diseases in the Chinese and Caucasian populations.