Meiosis errors in over 20,000 oocytes studied in the practice of preimplantation aneuploidy testing.

Reproductive Genetics Institute, 2825 N Halsted St., Chicago, IL 60614, United States.
Reproductive biomedicine online (Impact Factor: 2.68). 01/2011; 22(1):2-8. DOI: 10.1016/j.rbmo.2010.08.014
Source: PubMed

ABSTRACT This study presents the world’s largest series of over 20,000 oocytes tested for aneuploidies, involving chromosomes 13,16, 18, 21 and 22, providing the data on the rates and types of aneuploidies and their origin. Almost every second oocyte (46.8%) is abnormal, with predominance of extra chromatid errors predicting predominance of trisomies (53%) over monosomies (26%) in the resulting embryos (2:1), which is opposite to monosomy predominance observed in embryo testing. Of the detected anomalies in oocytes, 40% are complex, so testing for a few most prevalent chromosome errors may allow detection of the majority of abnormal embryos. Chromosome 21 and 22 errors are more prevalent, while two different patterns of error origin were observed for different chromosomes: chromosome 16 and 22 errors originate predominantly from meiosis II, compared with chromosome 13, 18 and 21 errors originating from meiosis I. This provides the first evidence for the differences in the aneuploid embryo survival depending on the meiotic origin. Considering the problem of mosaicism, which is the major limitation of the cleavage-stage testing, the direct oocyte aneuploidy testing by polar body analysis may be of obvious practical value in improving accuracy and reliability of avoiding aneuploid embryos for transfer.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The spindle assembly checkpoint, SAC, is a surveillance mechanism to control the onset of anaphase during cell division. SAC prevents anaphase initiation until all chromosome pairs have achieved bipolar attachment and aligned at the metaphase plate of the spindle. In doing so, SAC is thought to be the key mechanism to prevent chromosome nondisjunction in mitosis and meiosis. We have recently demonstrated that Xenopus oocyte meiosis lacks SAC control. This prompted the question of whether Xenopus oocyte meiosis is particularly error-prone. In this study, we have karyotyped a total of 313 Xenopus eggs following in vitro oocyte maturation. We found no hyperploid egg, out of 204 metaphase II eggs with countable chromosome spreads. Therefore, chromosome nondisjunction is very rare during Xenopus oocyte meiosis I, despite the lack of SAC.
    Cell cycle (Georgetown, Tex.) 03/2014; 13(10). · 5.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Currently, maternal aging in women, based on mouse models, is thought to raise oocyte aneuploidy rates, because chromosome cohesion deteriorates during prophase arrest, and Sgo2, a protector of centromeric cohesion, is lost. Here we show that the most common mouse strain, C57Bl6/J, is resistant to maternal aging, showing little increase in aneuploidy or Sgo2 loss. Instead it demonstrates significant kinetochore-associated loss in the spindle assembly checkpoint protein Mad2 and phosphorylated Aurora C, which is involved in microtubule-kinetochore error correction. Their loss affects the fidelity of bivalent segregation but only when spindle organization is impaired during oocyte maturation. These findings have an impact clinically regarding the handling of human oocytes ex vivo during assisted reproductive techniques and suggest there is a genetic basis to aneuploidy susceptibility.
    Cell cycle (Georgetown, Tex.) 04/2014; 13(12). · 5.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess the feasibility, efficacy, and safety of rescue intracytoplasmic sperm injection (ICSI) in cases of fertilization failure, using a scientific literature search. Systematic review. Centers for reproductive care. Infertility patients with total or partial fertilization failure during an IVF cycle. An electronic literature search was performed in PubMed from 1992 through May 2013. The search was then expanded by using listed references from selected articles. Pregnancy rate. The secondary outcome measures were fertilization rate, normal fertilization rate, cleavage rate, birth rate, and malformation rate. Thirty-eight studies including 1,863 patients were included. The pooled pregnancy rate was 14.4%; 194 babies were delivered. Rescue ICSI can result in the delivery of a healthy newborn, although the pregnancy rates are low. The clinical evidence did not indicate an elevated rate of malformations, although the data are limited and incomplete.
    Fertility and sterility 01/2014; · 3.97 Impact Factor