57. ADDITIONAL DATA FOR CONTROVERSIAL INTER-CHROMOSOMAL EFFECT SUSCEPTIBILITY IN PGT-SR PATIENTS

Abstract

Introduction NGS based translocation testing has been widely used as the possibility of detecting other chromosomal aneuploidies. Some studies claimed that balanced translocation carriers may have an increased risk for aneuploidies unrelated to translocation due to inter-chromosomal effect (ICE). Translocation causes unusual segregation of chromosomes involved in translocation. Furthermore this rearrangement may have an effect on the segregation of other structurally normal chromosomes during meiosis. Here we present a report of aneuploidy and complex aneuploidy rates among the embryos derived from patients carrying balanced chromosomal rearrangements (reciprocal or robertsonian translocations). Materials and Methods Whole Genome Amplification (WGA) was performed using SurePlex DNA Amplification System (Illumina, USA) and DOPlify (PerkinElmer Health Sciences - Australia). on biopsied cells. Veriseq PGS kit was used for further processing of WGA samples. BlueFuse Multi Software was used to analyse the data obtained from Miseq System. Results In this study, we collected 705 embryos from 168 patients with an average age of 31. At least one of the couples was previously reported to be a translocation carrier. According to our findings, 25.6% of these embryos was euploid and 69,4% was aneuploid/complex aneuploid (mosaic embryo results were excluded). 29.33% aneuploidy was detected in translocation of interest only. The rest (39.43%) was due to aneuploidy of other chromosomes . According to our in house PGT-A data (7200 embryos collected from 2177 patients) sum of aneuploidy and complex aneuploidy rates was 45.8. Overall these results fail to provide any support for the presence of an ICE. Conclusion In balanced chromosomal rearrangement carriers PGD by NGS array not only detects unbalanced chromosomal rearrangements due to chromosomes involved in translocation but also detects the possibility of other chromosomal aneuploidies. According to our findings, aneuploidy and complex aneuploidy rates do not increase in the embryos obtained from PGT-SR group of patients. Moreover, in addition to translocation chromosomes, we observed an additional aneuploidy risk related to other chromosomes in these embryos. Our data supports previous studies suggesting that ICE in embryos derived from balanced chromosomal rearrangement carriers is elusive. On the other hand average maternal age of PGT-A patients is significantly higher than PGT-SR group (35.1 vs 31.2 respectively). Although it is thought that increased maternal age may cause aneuploidy in some of the cases, some embryos have an increased aneuploidy rate regardless of maternal age. Nevertheless euploid embryo ratio in PGT-SR group is compared to PGT-A is relatively lower (25.6 vs 36.7) thus our results emphasize the importance of 24 chromosome scan in embryos derived from balanced translocation carriers NGS based translocation testing has been widely used as the possibility of detecting other chromosomal aneuploidies. Some studies claimed that balanced translocation carriers may have an increased risk for aneuploidies unrelated to translocation due to inter-chromosomal effect (ICE). Translocation causes unusual segregation of chromosomes involved in translocation. Furthermore this rearrangement may have an effect on the segregation of other structurally normal chromosomes during meiosis. Here we present a report of aneuploidy and complex aneuploidy rates among the embryos derived from patients carrying balanced chromosomal rearrangements (reciprocal or robertsonian translocations). Whole Genome Amplification (WGA) was performed using SurePlex DNA Amplification System (Illumina, USA) and DOPlify (PerkinElmer Health Sciences - Australia). on biopsied cells. Veriseq PGS kit was used for further processing of WGA samples. BlueFuse Multi Software was used to analyse the data obtained from Miseq System. In this study, we collected 705 embryos from 168 patients with an average age of 31. At least one of the couples was previously reported to be a translocation carrier. According to our findings, 25.6% of these embryos was euploid and 69,4% was aneuploid/complex aneuploid (mosaic embryo results were excluded). 29.33% aneuploidy was detected in translocation of interest only. The rest (39.43%) was due to aneuploidy of other chromosomes . According to our in house PGT-A data (7200 embryos collected from 2177 patients) sum of aneuploidy and complex aneuploidy rates was 45.8. Overall these results fail to provide any support for the presence of an ICE. In balanced chromosomal rearrangement carriers PGD by NGS array not only detects unbalanced chromosomal rearrangements due to chromosomes involved in translocation but also detects the possibility of other chromosomal aneuploidies.