A new study by researchers in China and the U.S. has found a way to identify a woman’s ‘bad’ egg cells, which could double the success rate of in vitro fertilization (IVF), or the process of fertilizing a woman’s egg with a man’s sperm outside of the body. This process could potentially lead to a quicker and safer way to guarantee healthy babies during the IVF process, the authors of the study claim.
Using this method, scientists could eliminate eggs with genetic defects, and instead safely choose genetically “normal” embryos to be produced. The researchers in the study searched for DNA sequence variations that were linked to genetic disorders, and also looked for chromosome abnormalities.
“In this way, we kill two birds with one stone: one set of deep sequencing analysis to avoid two types of genetic problems,” Jie Qiao, an author of the study and department director and professor of Gynecology and Obstetrics at Peking University, 3rd Hospital, said in a news release about the study. “Theoretically, if this works perfectly, we will be able to double the success rate of test tube baby technology from 30 percent to 60 percent or even more.”
In vitro fertilization is a method used by people who are infertile, or unable to have children. Once the egg is fertilized with the sperm in a laboratory “test tube,” the emybro is planted into the woman’s uterus.
Previously, scientists completing IVF procedures would screen for genetic defects, but these past ways of detection were risky — cells would have to be removed from the embryo, which could destroy them. This study showed for the first time that researchers were able to develop a way to safely remove cells without harming the embryo, through “whole-genome sequencing,” which is a process that can identify the whole DNA sequence of an organism’s genome, or genetic information. They were able to snag break-off cells that appear when egg cells divide then die off, called “polar bodies,” and extract their genomes in order to determine which egg cells were safe and which had defects.
The scientists will now turn to clinical trials to test their results. “If the clinical trial works, this technique could enormously increase the success rate of IVF, especially for older women or women who have had recurrent miscarriages,” Sunny Xie, a co-author of the study and Mallinckrodt Professor of Chemistry and Chemical Biology at Harvard University, said in the news release.
This process would be non-invasive and useful for couples who want to choose the “best” embryo to implant during in vitro fertilization. “A non-invasive way to do that analysis would be a fabulous development to improve live birth rates,” Josephine Johnston, a bioethicist at the Hastings Center in New York, told Nature.
However, Qiao says the procedure doesn’t necessarily allow people to create so-called “designer babies.” There is still uncertainty over how genes influence diseases and traits, so choosing certain desirable genes doesn’t necessarily guarantee anything.
Hou Yu, Fan W, Yan L, et al. Genome Analyses of Single Human Oocytes. Cell. 2013.