FERTILITY, IVF AND REPRODUCTIVE GENETICS: Edited by Emre Seli and Juan Antonio García VelascoMitochondrial DNA as a biomarker for in-vitro fertilization outcomeSeli, EmreAuthor Information Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut, USA Correspondence to Emre Seli, MD, Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, 310 Cedar Street LSOG 304B, New Haven, CT 06520-8063, USA. Tel: +1 203 785 7873; fax: +1 203 785 7819; e-mail: firstname.lastname@example.org Current Opinion in Obstetrics and Gynecology: June 2016 - Volume 28 - Issue 3 - p 158-163 doi: 10.1097/GCO.0000000000000274 Buy Metrics Abstract Purpose of review This article discusses the use of mitochondrial DNA (mtDNA) copy number as a potential biomarker for embryo viability in assisted reproduction. Recent findings Mitochondria have a well-established role in regulating embryo energy metabolism, and their efficiency has significant implications for reproductive success. Two recent studies suggested that elevated mtDNA copy number is associated with decreased implantation potential in human embryos generated by IVF. In the first study, Fragouli et al. reported that blastocysts that are aneuploid and those obtained from older reproductive age women have a higher mtDNA copy number. In addition, euploid blastocysts that failed to implant had a higher mtDNA copy number; and pregnancy did not occur when mtDNA copy number was above a threshold. In a subsequent study, Diez-Juan et al. found that mtDNA copy number inversely correlates with implantation potential of euploid embryos, not only for blastocysts but also for cleavage stage embryos. Instead of a threshold model, they proposed a score for embryos based on mtDNA copy number, which would be indicative of implantation potential. Unlike the previous study, Diez-Juan et al. did not find an age-associated decrease in mtDNA copy number in day 3 or day 5 embryos. Summary Recent reports suggest that mtDNA copy number may be used as a biomarker for embryo viability. Further studies are necessary to determine whether mtDNA copy number constitutes a parameter independent of morphology and preimplantation genetic screening and whether its use may result in higher IVF pregnancy rates. Copyright © 2016 YEAR Wolters Kluwer Health, Inc. All rights reserved.