Distribution of α1 immunoglobulin gene VNTR polymorphisms in Chinese

AIM: To investigate the polymorphisms of th e variable number tandem repeat (VNTR) in the α1 immunoglobulin gene in the Chi nese population and to compare them with the Caucasians. METHODS: 3 VNTR loci (VNTR1:α1 gene hs1,2 enhancer VNTR; VNTR2: 6 kb forward (change to upstream or down stream) the VNTR1 and E 5VNTR: locate d in the fifth exon) and their lengths in the α1 gene have been retrieved from th e genetic databases and literature. Genomic DNA was extracted from 201 healthy C hinese Han subjects. The sizes of the 3 VNTRs were determined by polymerase chai n reaction (PCR) and gel electrophoresis, and confirmed by sequencing randomly s elected samples. RESULTS: The VNTR1 locus revealed three different lengthed allel es, designated as α1A ,α1B and α1C for one, two and three repeat sequen ces, respectively, with the frequencies of 30.3%, 59.7% and 10.0%, respective ly. 6 genotypes were formed from the alleles with the frequencies of 12% for the AA; 32.3% for the AB; 37.8% for the BB; 4.5% for the AC; 11.4% for the BC; and 2.0% for the CC, respectively. Compared with the reported Caucasian popula ti o n the frequencies of the C allele and the BC、CC、AC genotypes were significantl y higher (P0.01), the A allele and the AB genotype frequencies were signi ficantly lower (P0.01). All the examined subjects showed the uniformed le ngths of 136 bp for the VNTR2 and 535 bp for E 5VNTR alleles. CONCLUSIONS: The repeat numbers of the VNTR1 of the α1 gene in the Chinese Han population are significantly different from the Caucasians with a higher C allele frequency and BC、 AC genotypes, and lower A allele frequency and AB genotype. We could not find evidence of polymorphism in the VNTR2 and E 5VNTR loci in the examined subjects. The results represent the first data from the Chinese population regarding the VNTR polymorphisms in the I alpha 1 gene, and provide a useful tool for the gene and the gene related studies.