New Test May Spot Which Embryos Stand Greatest Chance of Survival
Measuring mitochondria in cells better predicted success rate with in vitro fertilization, study says
The doctors reviewed the amount of mitochondrial DNA present in 219 embryos produced by 59 couples.
They found that mitochondrial DNA was elevated in the embryos produced by women in their late 30s and 40s, and also was elevated in embryos with the wrong number of chromosomes. The embryos that had the worst chromosomal abnormalities had the highest levels of mitochondrial DNA.
Researchers then implanted embryos that appeared healthy, regardless of their mitochondria levels. "These are embryos we would have high hopes for," Wells said. "They look good under the microscope. They did not have chromosome abnormalities."
However, only half of the implantations produced a baby.
Based on those findings, doctors established a threshold amount of mitochondrial DNA. "Embryos above that level never implant," Wells said. "About 25 percent of embryos that are chromosomally normal but fail to implant have these elevated levels of mitochondrial DNA."
They verified their findings by repeating the test on a second set of embryos using next-generation genetic sequencing. "It appears this is a genuine phenomenon," Wells said.
Chromosome screening is an expensive procedure, costing about $3,000, but Wells said a mitochondria screen could be added to the same procedure without increasing the cost.
"The mitochondrial screen could potentially be a free add-on on top of chromosomal screening," he said, given that both require a physician to take a few cells from the embryo and pass them on to a genetics lab. "Once you've got those cells, you might as well do as much as you can with them."
Wells warned, however, that the screen only sorts the potential viability of embryos. "These kind of tests aren't a magic bullet. They aren't going to make the embryos any more viable," he said. "In some IVF cycles, you're not going to get any viable embryos."