Diagnosis failure in preimplantation genetic diagnosis (PGD): poor technique or bad embryos?

Abstract

Objective: To investigate the causes of diagnosis failure observed in the course of PGD. Design: In the course of 41 PGD cycles performed by the Béclère-Necker hospitals in Paris within a one year period, we correlated the efficiency of diagnosis with embryo grades and their developmental potential. Materials/Methods: We started our newly created PGD program in November 1999 and have performed 41 cases in just over a one year period. Patients were hyperstimulated using GnRh agonist and Recombinant FSH. The embryos were cultured in IVF (MediCult) until day 2 and placed in M3 (MediCult) until day 3. One or two cells were removed from each embryos by cleavage stage embryo biopsy on day 3 using a fertilase laser for zona drilling in G2.2 medium (JCD). The embryos were then placed in G2.2 until the transfer procedure on day 4. PGD was performed by PCR (23 cases) for a range of single gene defects or by FISH for X-linked recessive diseases (5 cycles) and translocations (13 cycles). Embryo grades on day 3 and signs of compaction on day 4 were recorded for each embryo and correlated with the availability of diagnosis. Grade 1 embryos had cells of even size with no or little fragmentation. Grade 2 had cells of even size with less than 20% fragments and grade 3 were highly fragmented embryos associated or not with cells of different size. Statistical significance of the results was calculated using a χ2 test. Results: Overall, a diagnosis could be obtained for 187 of the 237 embryos analysed (79%). From the 50 embryos for which no diagnosis could be obtained, 40 were of grade 3 (80%) on day 3 and only 7 showed signs of compaction (14%) on day 4. These data were significantly different from those obtained from the group of embryos for which a diagnosis was obtained in which 40% were of grade 3 and 40% subsequently compacted. Embryo grade on day 3 and signs of compaction on day 4 depending on whether a diagnosis was obtained. ∗TotalNumber of embryos on day 3 (%)Number of embryos on day 4 (%)Grade 1Grade 2Grade 3CompactedArrestedDiagnosis18741 (22)71 (38)75 (40)∗p < 0.001.75 (40)∗p < 0.001.112 (60)No diagnosis503 (6)7 (14)40 (80) ∗p < 0.001.7 (14) ∗p < 0.001.43 (86)Total23744 (19)78 (33)115 (48)82 (35)155 (65)∗ p < 0.001. Open table in a new tab Conclusions: No diagnosis could be obtained from 21% of the embryos biopsied, however our study demonstrates that most of these embryos had a poor morphology and a poor developmental potential. We can speculate that the blastomeres analysed from theses embryos were arrested with degraded DNA which was not longer a suitable target for PCR or FISH analysis. We conclude that most untyped embryos would not have been good candidates for transfer. Supported by: This work was supported in part by the AFM.