Preimplantation Diagnosis by FISH: The Rambam Experience

Abstract

Purpose: Our purpose was to summarize our experience gained using fluorescence in situ hybridization for preimplantation diagnosis at the Rambam Medical Center.

Methods: Seventy-three embryos (29 cycles) were analyzed for preimplantation diagnosis for the following indications: advanced maternal age (>39 years), X-linked diseases, poor-quality embryos, repeated failure in vitro fertilization cycles and fast-dividing embryos. An additional 38 embryos with unequal pronuclei size were examined for ploidy. Biopsy of embryonic blastomeres was performed at the six- to eight-cell stage. Five fluorescence probes, for chromosomes X, Y, 13, 18, and 21, were applied for ploidy detection.

Results: Eighty-four (87%) blastomeres of the 73 embryos analyzed showed clear signals. Six of the blastomeres were lost during spreading. Two of the embryos were destroyed following biopsy. No nucleus was found in five of the blastomeres, while in nine, more than one nucleus was verified. Transfer was performed in 10 patients (32 embryos). Two pregnancies were achieved. Two healthy babies were born. Fifty-seven percent of the fast-dividing embryos demonstrated normal signals. In two groups of embryos of unequal pronuclei size, following conventional insemination and intracytoplasmic sperm injection, 50 and 11.4% demonstrated normal signals.

Conclusions: The efficiency of florescence in situ hybridization for aneuploidy detection is 87 and 97% for autosomes and gonosomes, respectively. The preimplantation genetic diagnosis is suitable for selected in vitro fertilization cases including fast-dividing embryos and embryos with unequal pronuclei size following regular in vitro fertilization.