"Designer babies" aren't going to be a reality anytime soon, researchers say.
Concerns about genetically altering embryos to have desired traits have been around nearly as long as in vitro fertilization (IVF) and the technology to screen embryos have existed.
But while recent live births resulting from embryonic CRISPR gene editing have re-focused attention on the issue, the most practical current use of genetic technology in embryos is genetic screening of IVF embryos before they're implanted in the womb, the researchers said.
Compared to targeting genetic diseases caused by a single mutation, the ability to select for specific traits that are influenced by multiple genes is more complicated than many people realize, according to the authors of the study published Nov. 21 in the journal Cell.
"The ability to do genomic sequencing of embryos is much easier than it was even five years ago, and we know many more gene variants linked to certain traits," said study co-corresponding author Shai Carmi, from the Hebrew University of Jerusalem.
"But selecting embryos for particular traits is very controversial except when it relates to a serious disease like cystic fibrosis. It raises many issues related to eugenics and unequal opportunities," Carmi explained in a journal news release.
In the new study, the researchers used computer simulations to assess the feasibility of selecting embryos based on each of two traits caused by multiple genes -- IQ and height -- and concluded that current genetic knowledge is unlikely to be sufficient to achieve a substantial increase of those traits in IVF embryos.
"There is much about these traits that is unpredictable," Carmi said. "If someone selected an embryo that was predicted to have an IQ that was two points higher than the average, this is no guarantee it would actually result in that increase. There is a lot of variability that is not accounted for in the known gene variants."
The U.S. National Library of Medicine has more on IVF.