Effect of chromosomal translocations on the development of preimplantation human embryos in vitro

OBJECTIVE: To determine the reliability of a new technique for single human blastomere karyotyping during clinical cases for preimplantation genetic diagnosis of translocations. DESIGN: Controlled clinical study. SETTING: Preimplantation genetic diagnosis and IVF program. PATIENT(S): Nineteen preimplantation genetic diagnosis cases with 11 types of translocations (10 reciprocal and one Robertsonian) involving chromosomes 1, 5, 7, 8, 9, 11, 12, 13, 14, 15, 16, 18, 20, 21, and 22. INTERVENTION(S): Blastomere biopsy followed by blastomere nucleus conversion into metaphase chromosomes. Fluorescent in situ hybridization (whole chromosome painting) was used for the detection of chromosomally unbalanced preimplantation human embryos.Main Outcome Measure(s): Percentage of informative metaphase plates and effect of unbalanced translocations on preimplantation embryo development. RESULT(S): Informative metaphases were obtained for 84% of the blastomeres. Analysis of preimplantation development of the resulting embryos showed that an unbalanced chromosomal complement does not affect embryo ability to reach the blastocyst stage in vitro. CONCLUSION(S): For the translocations tested, there is no evident selection against chromosomally unbalanced embryos at the preimplantation stage of embryo development.