Preimplantation genetic diagnosis for cancer risk during IVF is feasible, study indicates

It is now
scientifically feasible to use preimplantation genetic diagnosis (PGD) during
IVF to screen embryos for genes associated with high cancer risk, scientists
say.

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.