The test, called MitoGrade, works by measuring the levels of abnormal mitochondrial DNA present in embryos, allowing doctors to determine which embryos are most viable for a successful pregnancy.
Mitochondria are structures found within cells that are responsible for generating the energy cells need to function. Each mitochondrion contains small amounts of DNA, known as mitochondrial DNA.
It emerged in recent years that the number of chromosomes in an embryo can influence the outcomes of in vitro fertilization (IVF). But more recently, researchers from the University of Oxford and genetics laboratory Reprogenetics – both in the UK – found that the levels of mitochondrial DNA in embryos is a key factor in IVF success.
According to study leader Dr. Elpida Fragouli – of Reprogenetics – and colleagues, around a quarter to a third of embryos have excess levels of mitochondrial DNA, which means they will never result in a successful pregnancy.
“Embryos with elevated levels of mitochondrial DNA never seem to implant,” notes study coauthor Prof. Dagan Wells, of the Department of Obstetrics and Gynecology at the University of Oxford. “It’s something to do with energy production that isn’t quite right. It’s given us a new biomarker.”
What is more, the researchers found that as women age, levels of mitochondrial DNA in embryos increase, which may be a key factor in reproductive aging.
Test will help doctors select most viable embryos
The MitoGrade test involves the removal of a small number of cells from embryos called blastocysts. These cells are then assessed for levels of mitochondrial DNA.
“This will help guide doctors to the IVF embryos with the greatest chance of producing a viable pregnancy,” says Dr. Fragouli.
Commenting on their findings, Prof. Wells says:
“Currently, only about 1 IVF treatment in every 3 succeeds in helping a couple to have a baby. Anything that reduces the number of unsuccessful embryo transfers that patients have to endure will certainly be welcome. This important discovery indicates that mitochondria represent an important piece in the complex jigsaw puzzle that is infertility.”
The test is already being trialled in a number of fertility clinics in the US, including the New York University Fertility Center, NY.
At the American Society for Reproductive Medicine (ASRM) annual meeting held in Baltimore, MD, the researchers announced initial results from the first 100 American women to receive IVF using MitoGrade.
They revealed that IVF with the new test increased the likelihood for a successful pregnancy by 10% for women in their mid-30s, and the team believes the test is likely to lead to IVF success rates of 70-80%.
While the researchers are unsure what causes excess levels of mitochondrial DNA, this is something they plan to investigate in future research.
Meanwhile, the team will continue the US trials of MitoGrade, and they have applied to British IVF regulator – the Human Fertilisation and Embryology Authority (HFEA) – asking for permission to trial the test in the UK.
In August, Medical News Today reported on a study in which researchers detailed a new IVF approach that they say could boost success rates for older women. The technique involves harvesting a woman’s eggs, or oocytes, earlier – when the oocyte follicles reach 16 mm in diameter, rather than the standard 19-21 mm.
Written by Honor Whiteman