Short communication Mutation-free baby born from a mitochondrial encephalopathy, lactic acidosis and stroke-like syndrome carrier after blastocyst trophectoderm preimplantation genetic diagnosis Björn Heindryckx a, ⁎ ,1 , Jitesh Neupane a, ⁎ ,1 , Mado Vandewoestyne b , Christodoulos Christodoulou a , Yens Jackers b , Jan Gerris a , Etienne Van den Abbeel a , Rudy Van Coster c , Dieter Deforce b , Petra De Sutter a a Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium b Laboratory for Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium c Department of Pediatric Neurology & Metabolism, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium abstract article info Article history: Received 12 April 2014 Received in revised form 18 August 2014 Accepted 18 August 2014 Available online 23 August 2014 Keywords: Mitochondrial DNA (mtDNA) Heteroplasmy Preimplantation genetic diagnosis (PGD) Blastocyst Trophectoderm biopsy To investigate the applicability of preimplantation genetic diagnosis (PGD), we used trophectoderm (TE) biopsy to determine the mutation load in a 35-year-old female with mitochondrial encephalopathy, lactic acidosis and stroke-like syndrome (MELAS). Transfer of a mutation-free blastocyst gave birth to a healthy boy with undetect- able mutation in any of the analyzed tissues. We found strong correlation among TE cells (r = 0.90) within blastocysts and also between cytoplasmic fragments and TE (r = 0.95). This is the first case of mutation-free baby born from a MELAS patient after TE biopsy and supports the applicability of blastocyst PGD for patients with mtDNA disorders to establish healthy offspring. © 2014 Elsevier B.V. and Mitochondria Research Society. All rights reserved. 1. Introduction Mitochondrial inheritance in mammals is uniparental since mito- chondria in the offspring are exclusively transmitted through the maternal lineage (Birky, 2001; Chiaratti et al., 2011; Poulton et al., 2010). More than 150 mitochondrial mutations are reported associated with disorders in human (Levinger et al., 2004). Pathogenic mtDNA mu- tations usually occur in a state called “heteroplasmy” when cells contain both wild type and mutated mtDNA copies. The proportion of mutated copies is estimated by measurement of the mutation load in the cells. The presence of pathogenic mtDNA does not immediately lead to a fatal outcome of the cells or tissues as wild-type mtDNA copies can par- tially compensate for the mutated ones. Still, largely depending on the threshold of mutation load and the type of mutation, mtDNA mutations in humans can be associated with severe disorders for which no treatment is currently available. Hence, transmission to progeny should be prevented by developing accurate diagnostic tests or alternative treatment methods, which has generated a great deal of interest in the field of assisted reproductive technology (Poulton et al., 2010). According to the theory of random segregation of mtDNA during cell divisions and the genetic bottleneck, a stage during oogenesis is seen during which the number of mtDNA copies within the developing precursor oocyte is highly reduced. Hence, in patients who are carriers of mtDNA mutations, some oocytes can be found to be mutation-free. This was shown in earlier studies where whole oocytes were used to determine the mutation load, rendering them not useful for further clinical applications (Blok et al., 1997; Brown et al., 2001). Therefore, preimplantation genetic diagnosis (PGD) could be used to select mutation-free or oocytes/embryos with lowest mutation by determin- ing the mutation load either in polar bodies (PB) or in blastomeres. Importantly, the measured mutation load should be representative for the entire oocyte or embryo. Using heteroplasmic mitochondrial mouse models, levels of heteroplasmy in the first and the second polar bodies correlated well with that found in the respective oocytes and zygotes (Dean et al., 2003; Sato et al., 2005). In contrast, a modest to poor correlation and a wider variability in the levels of mtDNA heteroplasmy were observed in a recent study between PBs and their corresponding oocytes and zygotes in a heteroplasmic mitochondrial mouse model (Neupane et al., 2014). The latter study also showed higher Mitochondrion 18 (2014) 12–17 ⁎ Corresponding authors. Tel.: +32 9 332 4748, fax: +32 9 332 4972. E-mail addresses: bjorn.heindryckx@ugent.be (B. Heindryckx), jitesh.neupane@ugent.be (J. Neupane), mado.vandewoestyne@gmail.com (M. Vandewoestyne), christodoulos.christodoulou@uzgent.be (C. Christodoulou), yens.jackers@ugent.be (Y. Jackers), jan.gerris@uzgent.be (J. Gerris), etienne.vandenabbeel@uzgent.be (E. Van den Abbeel), rudy.vancoster@ugent.be (R. Van Coster), dieter.deforce@ugent.be (D. Deforce), petra.desutter@ugent.be (P. De Sutter). 1 Joint first authorship. http://dx.doi.org/10.1016/j.mito.2014.08.005 1567-7249/© 2014 Elsevier B.V. and Mitochondria Research Society. All rights reserved. Contents lists available at ScienceDirect Mitochondrion journal homepage: www.elsevier.com/locate/mito