10 July 2012
IVF Pregnancy Rates Increased Through Full Chromosomal Testing
Dr Leeanda Wilton, Scientific Director Preimplantation Genetics at Virtus Health, presented at the world’s largest annual specialised reproductive medicine meeting, ESHRE, her award winning research (1) into 24Sure Array CGH (comparative genomic hybridization), the technology that has been shown in an American study (2) to increase IVF pregnancy rates by up to 65%.
Advanced Embryo Selection introduced at Melbourne IVF, part of Virtus Health, over 18 months ago uses 24Sure Array CGH technology in Preimplantation Genetic Diagnosis (PGD) to screen all 24 chromosomes in a single cell biopsied from a day 3 embryo, allowing selection of the embryo with the greatest likelihood of pregnancy success.
Dr Leeanda Wilton said the successes at Melbourne IVF mirror those published in the American study.
“Through our Advanced Embryo Selection program, large numbers of embryos have been successfully biopsied and tested using 24Sure Array PGD technology in our East Melbourne laboratory.
“Patient groups treated at Melbourne IVF include those of advanced maternal age and those who have had multiple unsuccessful standard IVF treatment cycles; in these groups which have a low chance of success, the IVF success rate has doubled,” Dr Wilton said.
Research conducted by Dr Wilton and her team at Melbourne IVF was awarded Best Scientific Paper at the World Congress on Human Reproduction in 2011, and Dr Wilton was invited to present this paper at ESHRE 2012, Chromosomal mosaicism in embryos from young ART patients determined by array comparative genomic hybridisation (aCGH). This research aimed to better understand the genetics of human embryos.
“My research specifically looked at chromosomal mosaicism, which is a condition when the cells within an embryo have a different chromosomal make up. This is important to understand, as when we are testing a single cell for chromosomal errors, we assume that this cell represents the rest of the cells within that embryo,” Dr Wilton said.
“My research has rewritten our understanding of the embryos’ chromosomal make up and confirmed our long held belief that with the ability to analyse all 24 chromosomes, biopsy of a single cell from a day 3 embryo, produces reliable and accurate outcomes,” Dr Wilton said.
To perform Advanced Embryo Selection, a single cell is biopsied (removed) from the embryo on day three of development in the laboratory, and the DNA from the cell’s nucleus is multiplied thousands of times before being placed on a microarray, or DNA chip, where it is compared with normal male and female DNA. This allows the accurate detection of chromosome errors, increasing the chance of a healthy baby resulting from the transfer of a chromosomally normal embryo.
Melbourne IVF pioneered earlier forms of full chromosomal testing using single cell CGH from the mid-1990s, and reported the world’s first baby from this technology in 2001.
Dr Wilton, who is also Chair of the European Society of Human Reproduction and Embryology PGD Consortium’s Array Working Group, said the significance of Advanced Embryo Selection is its ability to perform rapid testing on a single cell.
“Using Advanced Embryo Selection, testing can be performed on a single cell from a day 3 embyro, whereas similar forms of technology require embryos to develop to the blastocyst stage on day 5 in order for several cells to be available for testing,” Dr Wilton said.
“About 50% of all embryos fail to reach the blastocyst stage on day 5, and this means a number of IVF patients have no embryos that can be tested. Some of these embryos are viable and can result in live births.
“At Melbourne IVF we have a number of pregnancies from embryos that were biopsied on day 3, were found to be chromosomally normal and went on to a successful pregnancy, yet would not have satisfied the criteria for a day 5 biopsy,” she said.
“Advanced Embryo Selection also provides accurate results within 30 hours, meaning IVF patients can undertake a fresh embryo transfer, and their treatment can continue uninterrupted, whereas in most cases embryos that need to be biopsied on day 5 must be frozen because the results are not available in time to perform a fresh embryo transfer.
“Our scientific team in Preimplantation Genetics is one of the most advanced in the world and we have the expertise and experience necessary to perform the testing here in Melbourne, analyse and interpret the results, giving patients the greatest confidence in their treatment outcome,” Dr Wilton said.
Advanced Embryo Selection is most suited to couples or single women where:
- 5 or more embryos have been replaced without success
- the woman is aged 38 or more
- there is a history of recurrent miscarriage
- there has been a previous pregnancy with a chromosome error e.g. Down syndrome
- ends -
1. Best Scientific Paper at the World Congress on Human Reproduction 2011, Chromosomal mosaicism in embryos from young ART patients determined by array comparative demonic hybridisation (aCGH), Dr Leeanda Wilton
2. Study Reference: The Journal of Molecular Cytogenetics by Yang et al 2012, 5:24 (2 May 2012)