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Aneuploidy rates in young egg donors are highly variable and may be related to the presence of a male factor, but are not predictive of cycle outcome.

Research presented at the American Society for Reproductive Medicine (ASRM), New Orleans, 2006.

L. Anderson, C. Adams, S. Wood. Reproductive Sciences Center, La Jolla, CA

OBJECTIVE: The use of preimplantation genetic diagnosis (PGD) to detect aneuploidy has traditionally been recommended principally for women ages 35 and over. Recently, however, it has been reported that young egg donors have a mean aneuploidy rate in excess of 50% (Munne et al, 2006). In the present study, we sought to explore whether the incidence of aneuploidy was associated with the clinical characteristics of the stimulation cycle or with the presence of a male factor. We also investigated whether the percentage of chromosomally abnormal embryos affected the clinical outcome of that cycle.
DESIGN: Retrospective analysis of data from 25 consecutive egg donation cycles in which PGD was performed in a private infertility center.
MATERIALS AND METHODS: Donors (mean age 24.8 ± 3.1, range 19 – 30) underwent ovarian stimulation using standard controlled ovarian hyperstimulation (COH) protocols. Days of stimulation, total dosage of gonadotropins and hormone levels on the day of hCG (E2, progesterone and LH) were reviewed. Following insemination by IVF or ICSI, day 3 embryos with a minimum of 6 cells were biopsied (n=219 of a total of 280 embryos, 78.2%) to remove 1 or 2 cells. Multi-color fluorescent in situ hybridization (FISH) was used to determine aneuploidy for chromosomes 13, 18, 21, X, and Y. Embryos were considered aneuploid if the PGD result indicated monosomy, trisomy, complex abnormal, haploidy or polyploidy. Biopsied embryos were evaluated for quality and progression to the blastocyst stage, and implantation and pregnancy rates were determined.
RESULTS: Among the 25 donor cycles, aneuploidy rates of biopsied embryos were highly variable, ranging from 0 to 80 percent (mean: 36.8 ± 23.3%). The rate of aneuploidy was not related to number of oocytes retrieved (mean: 16.9 ± 6.9), days of stimulation, amount of gonadotropin administered, peak follicular phase estradiol, or LH or progesterone on day of hCG. However, cycles involving a male factor had a trend towards higher aneuploidy rates compared to cycles with no male factor (means: 43.3% vs. 29.7%, respectively) In particular, there was a trend towards an increased incidence of complex abnormals, embryos with more than one abnormality (means: 25.0 % vs.16.6%). There was a low, but significant, negative correlation between embryo quality on day 3 and aneuploidy rate (r=-.34, p<.05). There was a similar weak negative correlation between the percentage of embryos reaching the blastocyst stage and the aneuploidy rate. There was no apparent relationship between aneuploidy rate and implantation rate (mean: 49.0%) or pregnancy rate (mean: 72.0%), but there was a trend towards lower implantation rates in the male factor group (39.3% vs. 60.9%).
CONCLUSIONS: Variable, and in some cases high, rates of aneuploidy were observed in embryos generated from egg donation cycles. There was no association of aneuploidy rate with any clinical parameter studied, however there was a relationship between elevated aneuploidy and the presence of a male factor. Given that embryo quality and progression to the blastocyst stage were only weak predictors of aneuploidy, consideration should be given to performing PGD in egg donation cycles, particularly if the egg donor has a history of a previous failed cycle or a male factor is present.