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Outcome of preimplantation genetic diagnosis of translocations
S Munné1, M Sandalinas, T Escudero
1The Institute for Reproductive Medicine and Science, Saint Barnabas Medical Center, Livingston, New Jersey, USA. santi.munne@embryos.net
Objective:
To review 35 cases of preimplantation genetic diagnosis (PGD) of translocations with several methods, including telomeric probes.
Design:
Retrospective study.
Setting:
Clinical IVF laboratory.
Patient(S):
Thirty-five couples with one partner carrying a chromosomal translocation.
Intervention(S):
PGD of translocation after polar-body or embryo biopsy.
Main Outcome Measure(S):
Pregnancy outcome.
Result(S):
Several trends were observed. First, PGD can achieve a statistically significant reduction in spontaneous abortion, from 95% to 13%. Second, the chances of achieving pregnancy are correlated with 50% or more of the embryos being chromosomally normal. Third, patients with robertsonian translocations produced fewer abnormal gametes and more pregnancies than did patients with reciprocal translocations. Fourth, a new fluorescence in situ hybridization protocol for PGD of translocations, which involves applying telomeric probes, has proved adequately reliable with a 6% average error rate.
Conclusion(S):
PGD of translocations achieves a statistically significant reduction in spontaneous abortion, both for polar-body and blastomere biopsy cases. Pregnancy outcome depended on the number of normal embryos available for transfer, with patients having <50% abnormal embryos achieving the most pregnancies. Because robertsonian translocations caused fewer abnormal embryos than reciprocal translocations, they also resulted in higher rates of implantation.