ESHRE launches international study of polar body screening
Jun 28, 2009 - 3:59:36 AM
Amsterdam, The Netherlands: The efficacy of preimplantation genetic screening (PGS) has been one
of the most hotly disputed subjects in assisted reproduction over the past few years. None of the trials
carried out so far has shown conclusively whether it works or not. Now the European Society of Human
Reproduction and Embryology (ESHRE) Task Force on PGS has decided to try to find out if a novel
method of doing PGS using polar body biopsy and chromosome array analysis offers a possible
Professor Joep Geraedts, ESHRE chairman, told the 25th annual conference of the society today (Sunday
June 28) that the Task Force would carry out a pilot study of PGS in one of each pair of 23
chromosomes in polar bodies, tiny cells that are a by-product of egg development, in collaboration with
BlueGnome, a DNA technology company based in Cambridge, UK. Once a pilot study has shown that
the technique is feasible, the researchers intend to carry out an international randomised trial.
The first phase will begin in September 2009 in two centres: the University of Bonn, Germany (Dr.
Markus Montag and Professor Hans van der Ven), and SISMER, Bologna, Italy (Dr. Luca Gianaroli and
Dr. Cristina Magli). Because this is a new technology, said Dr. Gianaroli, we need to carry out a
pilot study in order to be sure that the analysis can be completed within a time period that allows for
fresh transfer, as well as to ensure the reliable identification of the chromosomal status of an oocyte in at
least 90% of polar body biopsy attempts.
The two centres chosen for the pilot study have considerable experience in the field of polar body
biopsy because legislation in their countries restricts the possibility of undertaking embryo biopsy at a
later stage of development. The data from the study will be independently analysed by Dr. Sjoerd
Repping, from the Academic Medical Centre in Amsterdam, who carried out a randomised trial of PGS
on three-day old embryos published in 2007. The researchers hope to present the data at ESHRE 2010 in
Rome and to start the RCT with the involvement of at least six centres in different European countries
later the same year.
Oocytes to be used in the pilot phase will be obtained from volunteer patients who have given consent
for their use in this study. There will be no age restrictions on those donating their eggs.
By biopsying polar bodies at an early stage of egg development, the researchers believe that not only are
they using a less invasive method of chromosome analysis, but also a more accurate one. A biopsied
blastomere, or very early embryo, is not a true representation of the other cells in that same embryo,
said Professor Geraedts. This mosaicism confuses the analyses and we don't know what it means for
that embryo in the later stages of its development.
24sure, the novel molecular technique to be used in both phases of the trial was developed by
BlueGnome and is based on DNA amplification and microarray technology, which enables scientists to
look at all the chromosomes at the same time. This is, in theory, far more powerful than the method of
fluorescent in situ hybridisation or FISH, which has been used thus far.
It is because we think this subject is so important, said Professor Geraedts, that we have decided to
launch our first-ever clinical study. We hope that we will be able to answer the outstanding questions
about PGS once and for all. If we can show that polar body screening works, it will be a major step
forward in improving IVF treatment for many women who have persistent difficulty in getting pregnant
and maintaining a pregnancy.
All rights reserved by RxPG Medical Solutions Private Limited ( www.rxpgnews.com )