Outcome of preimplantation genetic diagnosis of translocations

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 tra nslocation. 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 statistic ally 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 tran slocations produced fewer abnormal gametes and more pregnancies than did pa tients with reciprocal translocations. Fourth, a new fluorescence in situ h ybridization protocol for PGD of translocations, which involves applying te lomeric probes, has proved adequately reliable with a 6% average error rate . Conclusion(s): PGD of translocations achieves a statistically significant r eduction in spontaneous abortion, both for polar-body and blastomere biopsy cases. Pregnancy outcome depended on the number of normal embryos availabl e for transfer, with patients having <50% abnormal embryos achieving the mo st pregnancies. Because robertsonian translocations caused fewer abnormal e mbryos than reciprocal translocations, they also resulted in higher rates o f implantation. ((C) 2000 by American Society for Reproductive Medicine.)