Authors: Man Li*1, David L. Hill1, Hal Danzer1, Alan DeCherney2, Catherine Marin DeUgarte2, Thomas J. Kim1, Jackson Wu2, Brian Su1, Tina Koopersmith1, Kathleen Kornafel1, Gary Andrews1, Cindy Underberger1, Lisa Barberena1, Mark Surrey1. 1 ART Reproductive Center, 450 N. Roxbury Dr. Beverly Hills, Ca 90210 USA ,Dept. of Ob/Gyn, Geffen School of Medicine, UCLA
Objectives: This is a follow-up embryo study after Preimplantation Genetic Diagnosis (PGD) was performed by embryo biopsy and aneuploidy screening of chromosomes 13, 18, 21, X and Y. All aneuploid embryos were further cultured to day 6 and reanalyzed with FISH using the same chromosome panel to determine if concordance with the day 3 diagnosis exists.
Materials and Methods: Six hundred sixty human embryos were included in the study from 94 IVF/ICSI patients due to 1) AMA (≥35 years), 2) repeated IVF failures, and 3) recurrent spontaneous abortions. Single blastomeres were biopsied on day 3 at 4-12 cell stage. Chromosomes 13, 18, 21, X and Y were analyzed by Fluorescence in Situ Hybridization (FISH). Euploid embryos (on average 2.5/patient) were transferred back on day 4-6 post retrieval. All remaining embryos were further cultured to day 6, when reanalysis was performed.
Results: Of a total of 660 embryos, three hundred sixty seven (55.6%) were euploid, 281 (42.6%) were aneuploid and 12 (1.8%) were anucleated or had a nucleus loss. Of the 367 euploid embryos, two hundred thirteen were transferred in 85 patients (of these 44 (51.8%) patients became pregnant)).
From the remaining euploid embryos, sixty eight were frozen at day 5, while 86 were not considered suitable for transfer or cryopreservation on day 5 and were therefore discarded. All of the 281 embryos with aneuploidy were then cultured to day 6, and only 56 embryos (19.9 %) progressed to the blastocyst stage.
When FISH analysis was repeated using the same probes on these 56 blastocysts, 34 (60.7%) were confirmed aneuploid (trisomic, polyploid or monosomic) in concordance with their D3 single cell diagnosis. However, 22(39.3%) of the blastocysts were determined to be diploid. It was also noted that of the 207(73.7 %) aneuploid embryos arrested before day 6 as opposed to 32 (37.2%) of the euploid embryos.
Conclusion: PGD integrated into the IVF to select the appropriate embryo for transfer can increase pregnancy rate and reduce the miscarriage rate. Day 3 single cell aneuploid result can be confirmed in 60.7% of the Day 6 blastocyst.
Technical considerations such as overlapped FISH probe signals, hybridization failure or loss of nuclear materials during processing may account for a small part of the non-concordance. The majority of discordant day 3- day 6 results are due, we believe, to mosaicism in Day 3 embryos, and also that cleavage stage embryos have limited ability to “self correct” their chromosomal status.