Chinese researchers have genetically modified a gene in nonviable human embryos. The controversial work illustrates that many hurdles remain before gene editing to correct genetic diseases would be safe for clinical use, the team reports April 18 in Protein & Cell.
The researchers used gene-editing molecules called CRISPR/Cas9 to repair or replace the human beta-globin, or HBB, gene. When that gene is mutated, it causes an inherited blood disorder called beta thalassemia. Of 86 embryos injected with the editing molecules, only 11 had HBB repaired or replaced.
The editing molecules also altered other genes that the scientists hadn’t intended to touch. Such “off-target” editing and other unintended difficulties mean that the technology is not yet ready for clinical use.
Ethical considerations and safety concerns over such work recently led two groups of scientists to call for a moratorium on the use of gene editing in human eggs, sperm or embryos. Genetic alterations of those cells can be passed on to future generations.