Estimating Demand for Germline Genome Editing: An In Vitro Fertilization Clinic Perspective

To determine the relationship between the age of the female partner and the prevalence and nature of human embryonic aneuploidy. Retrospective. Academic. Trophectoderm biopsies. Comprehensive chromosomal screening performed on patients with blastocysts available for biopsy. Evaluation of the impact of maternal age on the prevalence of aneuploidy, the probability of having no euploid embryos within a cohort, the complexity of aneuploidy as gauged by the number of aneuploid chromosomes, and the trisomy/monosomy ratio. Aneuploidy increased predictably after 26 years of age. A slightly increased prevalence was noted at younger ages, with >40% aneuploidy in women 23 years and under. The no euploid embryo rate was lowest (2% to 6%) in women aged 26 to 37, was 33% at age 42, and was 53% at age 44. Among the biopsies with aneuploidy, 64% involved a single chromosome, 20% two chromosomes, and 16% three chromosomes, with the proportion of more complex aneuploidy increasing with age. Finally, the trisomy/monosomy ratio approximated 1 and increased minimally with age. The lowest risk for embryonic aneuploidy was between ages 26 and 30. Both younger and older age groups had higher rates of aneuploidy and an increased risk for more complex aneuploidies. The overall risk did not measurably change after age 43. Trisomies and monosomies are equally prevalent. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Most human pre-implantation embryos are mosaics of euploid and aneuploid cells. To determine the fate of aneuploid cells and the developmental potential of mosaic embryos, here we generate a mouse model of chromosome mosaicism. By treating embryos with a spindle assembly checkpoint inhibitor during the four- to eight-cell division, we efficiently generate aneuploid cells, resulting in embryo death during peri-implantation development. Live-embryo imaging and single-cell tracking in chimeric embryos, containing aneuploid and euploid cells, reveal that the fate of aneuploid cells depends on lineage: aneuploid cells in the fetal lineage are eliminated by apoptosis, whereas those in the placental lineage show severe proliferative defects. Overall, the proportion of aneuploid cells is progressively depleted from the blastocyst stage onwards. Finally, we show that mosaic embryos have full developmental potential, provided they contain sufficient euploid cells, a finding of significance for the assessment of embryo vitality in the clinic.

To determine whether blastocyst biopsy and rapid quantitative real-time polymerase chain reaction (qPCR)-based comprehensive chromosome screening (CCS) improves in vitro fertilization (IVF) implantation and delivery rates. Randomized controlled trial. Academic reproductive medicine center. Infertile couples in whom the female partner (or oocyte donor) is between the ages of 21 and 42 years who are attempting conception through IVF. Embryonic aneuploidy screening. Sustained implantation and delivery rates. We transferred 134 blastocysts to 72 patients in the study (CCS) group and 163 blastocysts to 83 patients in the routine care (control) group. Sustained implantation rates (probability that an embryo will implant and progress to delivery) were statistically significantly higher in the CCS group (89 of 134; 66.4%) compared with those from the control group (78 of 163; 47.9%). Delivery rates per cycle were also statistically significantly higher in the CCS group. Sixty one of 72 treatment cycles using CCS led to delivery (84.7%), and 56 of 83 (67.5%) control cycles ultimately delivered. Outcomes were excellent in both groups, but use of CCS clearly improved patient outcomes. Blastocyst biopsy with rapid qPCR-based comprehensive chromosomal screening results in statistically significantly improved IVF outcomes, as evidenced by meaningful increases in sustained implantation and delivery rates. NCT01219283. Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.