It is clear that the PGD world is going through a significant revolution and IVFAustralia (with our partners in Melbourne IVF) is at the forefront of it.
I was delighted to give a lecture last month on PGD at the Asian conference ‘Learning Initiatives for Fertility Experts’ in Ho Chi Minh City in Vietnam. It gave me an opportunity to review our own data at IVFAustralia, and to compare our service with what is published and what is done elsewhere.
PGD (Preimplantation Genetic Diagnosis) involves biopsy of embryos to assess the presence of either a specific genetic abnormality (eg. Cystic fibrosis or Huntingtons disease) or, more commonly, chromosomal abnormalities (eg. Down’s syndrome). This information is used to determine which embryo to transfer back.
IVFAustralia has led the move to array technology, which enables analysis of all 23 pairs of chromosomes from a single cell within 36 hours. This has led to a significant increase in demand for array PGD over the last 2 years. While most studies so far have focused on young IVF patients, demonstrating over 50% increases in pregnancy rates, success rates for more difficult cases including older women (eg. Over 40) and women with histories of repeated miscarriage or multiple IVF attempts are more modest. Still good, but clearly other factors need to be considered carefully for them – such as sperm quality, cycle control, uterine cavity factors and immune factors (NK cells).
Keep in mind also what is quoted from any study. Many women starting a potential PGD cycle do not create embryos of good enough quality for biopsy, and many embryos biopsied are abnormal and so are not transferred. The success rate quoted will vary enormously if based on the number of cycles started, or number of cases with embryo biopsy, or number of cases with a transfer. As a woman gets older, it is not uncommon for all embryos tested for chromosomes to be abnormal, and so many of those cases do not get a transfer. However, the diagnosis of such a problem is often very helpful in its own right: to consider why IVF isn’t working, to try different treatments, or to ultimately give up trying with her own eggs.
The debate over day 3 or day 5 biopsy is still very topical. Day 3 biopsy gives a couple more embryos to test (better overall diagnostically), and can be combined with fresh transfer on day 5 (all complete in the one cycle). Day 5 offers a more focused approach on fewer embryos. While appealing for laboratories (less embryos to test) and potentially safer for the embryos (this is still hotly debated), it also results in delayed transfer of frozen embryos (in the following month), and the possibility than some embryos that don’t make the grade for biopsy – but could still produce a baby – are discarded or not tested. IVFAustralia will soon be able to offer both, and we will then assess the pros and cons of each approach in more detail in a single unit.
The technology changes will soon be even more significant. Over the next few months IVFAustralia with Melbourne IVF are moving to Karyomapping for single gene testing which will provide a far faster process for preparation and treatment. And we will also soon be moving towards Next Generation Sequencing which will also be faster, hopefully cheaper, and enable even more comprehensive testing including chromosomes and single genes. This incredible technology is a spin-off from the Human Genome Project in which the entire genetic sequence of a human was first described in 2003. It took over 10 years and over $100,000,000 to do that work. We can now do it in 3 days at a cost of a few thousand dollars.
Now that is progress!
Dr Gavin Sacks is a specialist with IVFAustralia and writes regularly about the latest technological advances in fertility treatment and practice. For further information about Gavin click here.