[Implication of single nucleotide polymorphisms in association study: mitochondrial variations as another genetic...

Although multiple nuclear gene polymorphisms have been identified as potential risk factors for hypertension, the linkage between extranuclear DNA variations and hypertension has been uncertain. We investigated whether mitochondrial DNA(mtDNA) polymorphisms are implicated in Japanese hypertension. We used direct sequencing methods to search for single nucleotide polymorphisms(SNPs) in a hypervariable segment of the mitochondrial control region in each blood sample from 20 hypertensives and 20 normotensives. Then, we determined the distribution of two SNPs, T16223C and C16362T, in 183 hypertensives and 193 healthy subjects in the Aomori population in the northern area of Honshu island of Japan. The relationship between the gene polymorphism and hypertension was evaluated using chi-square test. Seventy SNPs were found there and the number of SNPs in each individual was significantly greater(p = 0.0111) in hypertensives than in normotensives. The C16223 genotype was more frequent in hypertensives than in normotensives(p = 0.0018). There was no significant difference in C16362T variant frequency between the groups. From these results, we conclude that mtDNA SNPs were enriched in Japanese hypertension and that the mtDNA C16223 genotype may be one of the genetic susceptibility factors for hypertension.