Treatment-related chromosome abnormalities in human embryos

TLDR

The study examined mosaicism in high‑quality embryos from four centres to evaluate how follicular induction and laboratory exposure affect chromosomal status. Embryos were fully biopsied and analyzed by simultaneous FISH probes for chromosomes X, Y, 13, 18, and 21. Mosaicism first appeared at the first, second, or third cell division, varied markedly between centres, was more common before 1991, and suggests that culture conditions or hormonal protocols can induce chromosomal abnormalities, potentially explaining differing pregnancy rates across IVF centres.

Abstract

Mosaicism was studied in good quality embryos from four different centres in order to assess the effects of follicular induction and exposure to laboratory conditions on chromosomal status. The donated embryos were fully biopsied and analysed by fluorescence in-situ hybridization using probes for chromosomes X, Y, 13, 18 and 21, simultaneously. The number of abnormal cells present indicated the division at which mosaicism first occurred (4/4 cells at first division, 2/4 cells at second, 2/8 at third). The rate of mosaicism in embryos from different centres varied greatly (P < 0.001). Most of the mosaic embryos were obtained before 1991. In one clinic increased mosaicism was found in embryos obtained before 1991 when compared to embryos obtained thereafter. The results suggest that certain culture conditions and/or hormonal stimulation protocols may induce chromosomal abnormalities and partly explain differences in pregnancy rates between in-vitro fertilization centres.