July 5, 2007

new study on preimplantation genetic screening

Scientists commented on work presented at the annual meeting of the European Society of Human Reproduction and Embryology which cast doubts on the effectiveness of preimplantation genetic screening.

Professor Alan Handyside, director of The Bridge Fertility, Gynaecology and Genetics Centre, said:

“Detailed follow up of developmental and chromosomal abnormalities in embryos is an extremely powerful way of assessing risk for some patients.

“We should target PGS for patients who we know or can show are at high risk.

“It is dangerous for people to be saying that PGS has no clinical benefit. This is simply not our experience and may deprive high risk patients of treatment they need.

“PGS can be very effective for embryo selection, screening and diagnosis if applied to the appropriate population.”

Dr Alan Thornhill, scientific director at The Bridge Fertility, Gynaecology and Genetics Centre, said:

“The study concludes that we shouldn’t apply PGS routinely to women over 35, but we don’t do this and I don’t know any clinic in the UK who does.

“Considering the patients are not targeted, these results are not surprising . The danger in over-interpreting these results is that women who are at high risk of having chromosomally abnormal embryos will not receive the treatment they need.

“Even with the limitations of the current test, we are convinced that PGS has value to some patients.

Patients need to be targeted for PGS to be effective. We are convinced that intelligent application of PGS will benefit some patients.”

Alison Lashwood, consultant nurse in Genetics and Pre-Implantation Genetic Diagnosis at Guy’s and St Thomas’ NHS Foundation Trust, said:

“This case once again raises many complex issues for the mother, her daughter and clinicians who are asked to offer such treatment. Provided that the associated psychological needs and expectations of both mother and daughter are considered in a timely, realistic and responsible manner by relevant health professionals then this case of egg donation by known donor may represent an opportunity for this girl with TS to have a family of her own in the future.”

Dr Frances Flinter, clinical director of Children’s Services and Genetics at Guy’s and St Thomas’ NHS Foundation Trust, said:

“It is always tempting to follow technology and offer an increasing range of tests on embryos in an attempt to improve those likely to implant, especially for women whose chance of success following IVF is small. Studies now demonstrate, however, that preimplantation genetic screening increases the cost of treatment but actually decreases the chance of establishing a pregnancy and therefore it should not be offered to women having IVF for infertility. The situation is different for couples where one or both potential parents is known to carry a specific genetic abnormality, for whom any future pregnancy is at high risk of being affected, as preimplantation genetic diagnosis with testing for that specific abnormality has been proven to increase the success rate.”

Alison Murdoch, Professor Of Reproductive Medicine, Newcastle Fertility Centre At Life, said:

“This is an important study that adds to the growing body of evidence showing that PGS is not beneficial. Furthermore, there is now concern that it might even reduce pregnancy rates. It illustrates the importance of undertaking properly controlled studies before new techniques are introduced as clinical procedures. Patients who pay for PGS as part of their IVF treatment should be made aware of these results.”

Dr Richard Kennedy, spokesperson for the British Fertility Society and Infertility Specialist at University Hospital Coventry, said:

“The place for PGS has never been completely established for age related aneuploidly. This important study adds further evidence to support the view that PGS should not routinely offered in women undergoing IVF treatment in the older age groups. “

Peter Braude, Professor of Obstetrics & Gynaecology, Kings College London, said:

“At last a reputable group has been in the position to do a proper trial of assessment of PGS for infertile patients of advanced maternal age seeking IVF – the most common indication. The study has been well conducted and uses clinical outcome (continuing pregnancy and live birth) rather than the implantation rate as in some previous papers. It is also about patients not just cycles, as it analyses its use in three cycles.

“The results clearly add weight to previous proper trials which demonstrate that PGS doesn’t work for advanced maternal age. Vulnerable patients should no longer be exploited financially under the impression and holy belief that it does. A similar study should be undertaken for PGS use in repeated IVF failure and recurrent miscarriage other techniques in which it is purported to work.”