Preimplantation Genetic Diagnosis for Aneuploidy Screening (PGD-AS) using a 9 probe chromosome panel: High prevalence of abnormal embryos and no embryo transfer in older women
M. Doyle, J. Gagne, Vincent, M. Perretti.
Connecticut Fertility Associates, Bridgeport, CT
Objective: The purpose of this investigation was to evaluate the clinical utility of preimplantation genetic diagnosis for aneuploidy screening (PGD-AS) using a 9 probe chromosome panel in patients undergoing IVF.
Design: Retrospective analysis of data from a private IVF center in the USA.
Methods: This evaluation included data from 73 women (n=652 embryos) who underwent IVF with PGD-AS in 2004. Reasons for PGD-AS included advanced age, recurrent abortion, and/or repeated IVF failure. Patients were grouped according to 2 age groups (<40 yrs and > 40 yrs). Embryos from each patient were biopsied, analyzed and diagnosed at a reference laboratory using a 9 probe chromosome panel. Embryos were considered abnormal if the PGD result indicated monosomy, trisomy, complex abnormal or haploid. We also assessed whether or not patients in each group had an embryo transfer, based on the PGD result. Data were analyzed using Chi-square for aneuploidy rate and Fisher’s Exact test for the percentage of patients with no embryo transfer. Statistical tests were not used when comparing pregnancy rates since the power of the test would be below the desired power based on the number of patients.
Results: In general, the rate of abnormal embryos in both groups was high, however the > 40 group had a significantly higher abnormal rate compared to the younger group. Interestingly, the older group also had a much higher percentage of patients with no embryos available for transfer, based on the PGD result. Pregnancy rate per embryo transfer was similar between the groups, but appeared to be high in the older group if compared to our program’s historical results (data not shown). Moreover, the PR/ET was higher (clinically) compared to the PR/patient in the older group.
| Age Group | # Embryo Biopsied | # Embryo normal | Abnormal Rate (%) |
Pts with no ET(%) |
PR/ET | PR/Pt |
|
< 40 yrsn=44 |
389 | 121 | 69% |
4.5 %(2/44) |
40.5%(15/37) |
38.5%(15/39) |
|
> 40 yrsn=29 |
253 | 47 | 81% |
31 %(9/29) |
44.4 %(8/18) |
29.6%(8/27) |
| p value | <0.001 | 0.005 |
Conclusion: It appears that PGD using a 9 probe chromosome panel results in a high percentage of embryos diagnosed as abnormal, especially in women 40 yrs and older. A recent abstract from Sarajari et al. (PCRS, 2005) reported an abnormal rate of about 62% in a group of patients with a mean age of 37 yrs old. Notably, a greater percentage of women in the older group had no embryos available for transfer based on the PGD result. Despite the high rate of abnormal embryos in the >40 group, the reported pregnancy rates may suggest that PGD provided some clinical benefit in the selection of embryos for transfer. We continue to assess the clinical utility of PGD for aneuploidy screening in our IVF program.
