Total fertilization failure and molecular abnormalities in metaphase II oocytes

Total fertilization failures (TFF) are rare events of IVF by intracytoplasmic sperm injection (ICSI). When male factor is excluded, the lack of identifiable aetiological criteria raises the question of the reliable clinical management. The goal of this study was to identify molecular abnormalities in metaphase II (MII) oocytes yielding TFF. The nuclear mature MII oocytes mRNA expression profiles were compared between a 30-year-old patient who had experienced three successive TFF (egg number = 39) and control patients with fertile cohorts diagnosed with tubal or male infertility. The mRNA abundance for the 30,000 genes of the genome was evaluated by microarray and, for selected genes, by quantitative-polymerase chain reaction analysis. Transcriptional analysis of unfertilized MII oocytes revealed an altered gene expression profile associated with TFF. Meiosis, cell growth and apoptosis controlling genes were mis-expressed with important fold changes. The results reveal that, despite passing the pre-IVF morphological examination, high-grade oocytes may carry substantial molecular abnormalities at the gene expression level associated with failure of MII oocyte activation. In the absence of an identifiable defect causing TFF, this microarray approach allows improvement of clinical therapeutic management: informed counselling about alternate therapeutic solutions could be proposed.