New IVF test/genetic testing increases pregnancy chances, say researchers
A technique for screening embryos for genetic defects doubles the chances that one will implant in the womb, according to a pilot study by UK and US researchers. These are still early days for this procedure but the initial results certainly look promising.
Genetic screening involves testing embryos produced during in-vitro fertilization for abnormal chromosomes that could prevent the embryos from being carried to term. One of the problems with the currently used technique, preimplantation genetic diagnosis (PGD) is that only one or two cells are analyzed for genetic defects during an IVF procedure which turns out to be not enough for a confident diagnosis in some cases.
The new technique, called comparative genomic hybridization (CGH), allows doctors to remove cells from the embryo at a later stage, when it is five days old and has more than 100 cells. it is still IVF but the embryo is older and more cells are tested so that statistically the test is more accurate. Also a smaller percentage of the total cells are removed for the test making it less potentially damaging to the embryo.
“The pregnancy rates we’ve got so far are absolutely phenomenal,” said Dr Dagan Wells at Oxford University and Reprogenetics UK, who led the study. “We’re ready to begin a trial in the UK, and we have a couple of license applications in to the Human Fertilisation and Embryology Authority to start offering CGH to patients.” The HFEA is the UK’s regulator of fertility clinics.
Dr Mandy Katz-Jaffe at the Colorado Centre for Reproductive Medicine, near Denver, who is part of the team, said: “The patients who are going through this knew this was their last chance of conceiving without going for donor eggs. They have a poor prognosis, with multiple failed cycles. The effect on those patients who have conceived has been beyond anything I can describe.” Wells’s team tested the CGH method in 23 women aged 30-42, and transferred 50 embryos. After screening and embryo transfer, 20 of the women became pregnant (fetal heartbeat confirmed by ultrasound). Two suffered miscarriages in the first three months, two have already given birth and four more are due before the end of the year.
Wells will present his results today (November 10, 2008) to the American Society of Reproductive Medicine’s annual conference in San Francisco.