Genetic Analysis of Blastocyst from Metaphase I like Oocytes with Indented Zone Pellucida

Abstract

Background: Previous cases reported that oocytes were characterized by indented zone pellucida (ZP) and narrow perivitelline space (PVS) with low oocyte maturity or all metaphase I (MI) like oocytes which usually be abandoned. These MI-like oocytes can be fertilized and develop embryo. The genetic analysis of blastocyst from MI-like oocytes with indented ZP and narrow PVS is still unknown. Methods: In this report, patient collected all immature MI-like oocytes with indented ZP and narrow PVS. Intracytoplasmic sperm injection (ICSI) proceed to these oocytes directly. The MI-like oocytes can fertilization, and developed blastocyst. The patient got pregnant after transfer 2 embryo on day 3. Blastomere biopsy, genome amplification, copy number variation (CNV) and single nucleotide polymorphism (SNP) analysis was performed. Results: CNV analysis showed that genotype was 46,XX, with mosaic of multiple chromosomes and SNP results showed that part of the chromosomes belong to triploids, and some belong to quadruplicate copies based on the B-allele frequency (BAF) value combined with the LogR Ratio. It is speculated that the cell is in the early stage of the first meiosis. Conclusion: MI like oocytes with indented ZP and narrow PVS can developed blastocyst and pregnancy after ICSI. Genetic analysis of blastocyst showed mosaic of multiple chromosomes.

Keywords

• ICSI
• MI like oocyte
• indented ZP
• narrow perivitelline space