09 July 2012
ByAppeared in BioNews 664
European researchers presented the results of a major study - as yet the largest in this area of research - at the European Society of Human Reproduction and Embryology's annual meeting in Istanbul, Turkey. They conclude that the technique can be used reliably so that men and women who carry cancer-causing mutations in their BRCA1 or BRCA2 genes do not pass them on to their children. Female carriers of a mutation in either gene have a 60 to 80 percent chance of developing breast cancer over their lifetimes, and a risk of 30 to 60 percent (BRCA1) or five to 20 percent (BRCA2) for ovarian cancer
The PGD procedure allows doctors to identify which embryos carry these genes, and therefore only implant ones that do not, thereby removing the mutation from the family tree.
The study looked at 145 cycles of IVF in 70 couples where one partner carried one of the BRCA mutations. A total of 717 embryos were created for these couples and grown for three days - when they would have comprised eight cells - at which point one cell was extracted and tested for the presence of a BRCA mutation.
Overall, 43 percent of the embryos were affected, while 40 percent did not carry the mutations and were considered viable. Using the unaffected embryos, the couples achieved a 41 percent pregnancy rate, or 42 pregnancies in 40 women in total.
'We now believe that this technique offers an established option for those couples seeking to avoid the risk of inherited BRCA in their children', said Professor William Verpoest, from the Vrije University in Brussels, who presented the study.
Speaking to the BBC, Mr Stuart Lavery, director of IVF at Hammersmith Hospital in London said that the study, published months earlier in the journal Human Reproduction, was 'quite an important paper'. He said that knowing that removing '12.5 percent of the whole genetic mass of the embryo' for testing did not to affect the embryo's viability was 'hugely reassuring'.In his presentation Professor Verpoest recognised the debates on the ethics of using PGD to screen for BRCA mutations. Cancers associated with the BRCA mutations occur late in life and therefore options for treating them are constantly improving. 'Controversy will still remain over the ethical acceptability of PGD for a susceptible, yet preventable condition', he said.