Enhanced Sensitivity of Early Fetal Genetics using the QIAamp Circulating Nucleic Acid Kit

Multiple gestation represents the principle complication with in vitro fertilization (IVF), causing increased maternal and neonatal morbidity compared with singleton pregnancies, and estimated to cost $1 billion annually in the U.S. Better methods of embryo selection are needed before routine single embryo transfer protocols can be successful. Studies involving the evaluation of the predictive value of new embryo selection methodologies require the ability to track which of the multiple IVF embryos transferred actually implanted. DNA fingerprinting has therefore become an extremely powerful tool in the development of markers of embryonic reproductive potential. We previously demonstrated that cell-free fetal DNA enriched from maternal circulation can be used to determine which embryo implanted at 9 weeks gestation, avoiding invasive methodologies such as CVS or amniocentesis, and providing for more rapid clinical trials (Treff et al. 2011, Molecular Human Reproduction, 17, 434–438). As a surrogate for performance of DNA enrichment, analysis of fetal gender using quantitative real time PCR for 9 Y chromosome loci was more recently performed here after using either the QIAamp Circulating Nucleic Acid Kit or QIAamp Virus Kit. Maternal peripheral blood at 9 weeks gestation from 40 patients was studied and compared to genders observed upon delivery. Assay specific sensitivity to the presence of Y chromosome DNA was significantly better using the Circulating Nucleic Acid Kit compared to the QIAamp Virus Kit (95% compared to 83%, respectively). Specificity for samples from pregnancies with a male fetus was 100% for DNA enriched using either kit. In conclusion, the QIAamp Circulating Nucleic Acid Kit provides enhanced sensitivity to cell-free fetal DNA from maternal circulation and provides an opportunity for increasing the quantity and quality of downstream applications.