While most couples using IVF do so because they have a fertility problem, in some circumstances it can be used to help families with inherited genetic diseases or women who have suffered repeated miscarriage.
During routine IVF cycles, embryos are created by bringing egg and sperm together in the laboratory. At Genea, the developing embryos are closely monitored for five or six days before the ‘best looking’ embryo is usually transferred into the uterus, with any others frozen for potential use in the future.
But while the embryos can appear to be developing normally when examined under the microscope, they may contain random chromosome problems or carry a gene mutation known to cause a particular disease. And for some families, where there is an identified risk of a couple passing on a genetic disease, IVF can be used and include screening of embryos.
It is possible to remove a small number of cells from an embryo five days into development – without risk of causing harm to the developing embryo. Those cells can them be screened for an identified genetic disease, such as cystic fibrosis, Huntington’s disease or Down syndrome.
So, using the screening technique called preimplantation genetic diagnosis (or PGD) alongside IVF gives couples the option of transferring an embryo that is known to be free of an identified genetic disease – and increase the likelihood of taking home a healthy baby.
For many couples, the alternative to using PGD would be to conceive naturally and have testing done during the second trimester. They then face the agonising decision of whether or not to continue with a pregnancy if the results reveal the baby is affected by the genetic disease.
Genea fertility specialist Dr Alison Gee says that many couples who consider the screening long for a healthy baby.
“The option of PGD for these families is very important – many couples will have already suffered the loss of a pregnancy or the death of a child and simply cannot go through this again,” Dr Gee says. “PGD allows the embryos to be screened for disease prior to transfer, alleviating extremely difficult decisions later into a pregnancy.”
Genea has one of the most successful PGD programs in the world and has developed tests to screen for more than 170 disorders.
It is also possible to screen embryos to check chromosomes and detect random problems that are one of the most common causes of IVF failure and repeated miscarriage.
The most successful technique that scientists can use for these problems, microarray comparative genomic hybridisation (CGH) was first used in Australia by scientists at Genea with dramatic results.
When women have repeatedly suffered miscarriages or failed IVF cycles or are faced with fertility declining rapidly due to their age, CGH can give the best possible chance of success, by transferring an embryo known to have the correct chromosome make up.
At Genea, pregnancy rates among couples using CGH screening are very encouraging. Where there is a chromosomally normal embryo to transfer after screening, almost nine out of ten patients aged under 38 achieve a pregnancy.
“Being able to identify which embryos are free of chromosome abnormalities has the potential to reduce both the emotional and the financial stress for patients undertaking IVF treatment. For that reason an increasing number of younger women aged 35 to 40 are also considering PGD testing of their embryos prior to transfer,” explains Dr Gee.