Variable Number of Tandem Repeat Polymorphism of the Endothelial Nitric Oxide Synthase Gene in Japanese Population
We examined the variable number of tandem repeat (VNTR) polymorphism at intron 4 of the human endogenous nitric oxide synthase (eNOS) gene. The alleles were amplified from genomic DNA samples by the polymerase chain reaction (PCR), and analyzed by agarose gel electrophoresis. The PCR products showed one or three reproducible bands and two alleles and one extra band could be identified. The nucleotide sequence data revealed that the larger allele, allele 2, was in good agreement with that of the VNTR region, whereas the smaller one, allele 1, lacked one 27-bp core unit. The extra band, which showed the largest molecule, always appeared when heterozygote samples were used as templates, indicating a heteroduplex structure resulting from mismatch of the heterozygous alleles during annealing. The allele frequencies were determined for 112 unrelated Japanese population. The estimated allele frequency was allele 2 = 0.87 and allele 1=0.13, and the heterozygosity was 0.226. The genotype frequencies were in good accordance with the Hardy-Weinberg equilibrium.