A case-control study of maternal blood mitochondrial DNA copy number and preeclampsia risk.

A growing body of evidence suggests that mitochondrial dysfunction is associated with oxidative stress and impaired differentiation and invasion of trophoblasts, both of which have been related to preeclampsia pathogenesis. However, studies that examined circulating mitochondrial DNA (mtDNA) copy number in relation to preeclampsia are limited. Therefore, we examined association of maternal whole blood mtDNA copy number (a novel biomarker of systemic mitochondrial dysfunction) with the odds of preeclampsia. This case-control study was comprised of 144 preeclampsia cases and 407 normotensive controls. Real-time quantitative polymerase chain reaction (PCR) was used to assess the relative copy number of mtDNA in maternal whole blood samples collected at delivery. Logistic regression procedures were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). Median mtDNA copy number was significantly higher among preeclamptic women compared with controls (271.5 vs. 239.3, Mann-Whitney U test p-value <0.001). There was evidence of a linear trend in higher odds of preeclampsia with increasing quartiles of mtDNA copy number (P for trend=0.03) after controlling for confounders. The adjusted ORs for the successive quartiles of mtDNA copy number, compared with the referent (first quartile) were 1.30 (95%CI 0.66-2.56), 1.93 (95%CI 1.02-3.67) and 1.86 (95%CI 1.00-3.48). Our findings suggest that maternal mitochondrial dysfunction may contribute to the pathogenesis of preeclampsia. However, replication in prospective studies is needed to further investigate this relationship.