The ISSCR is aware of reports that scientists in China have used CRISPR-mediated genome editing during in vitro fertilization to modify the genetic material of two embryos that were subsequently implanted into a patient, leading to the birth of two babies. As ISSCR and a number of other organizations have previously stated, the use of nuclear genome editing technologies, such as CRISPR, during fertility treatment is premature and should not be attempted at this time. The safety risks associated with potential unintended genetic changes in embryos remain uncertain.
Genetic modifications in embryos are likely to affect most cells in the body, including the germline, and therefore can be passed on to future generations. This causes a much higher level of concern about potential safety and unintended effects than with somatic gene therapy in which genetic modifications are engineered in only certain cells of the body, such as in blood cells to treat blood diseases.
The application of nuclear genome editing technology in the laboratory provides tremendous opportunities to understand human biology and disease, but any clinical application to human germline modification or human embryos used in fertility treatment should not go forward at the present time without careful deliberation on the significant ethical, societal, and safety considerations involved.
In its Guidelines for Stem Cell Research and Clinical Translation (Section 2.1), the ISSCR calls for broad public and international dialogue on the capabilities and limitations of these technologies and the implications of applying them to the human germ line. The ISSCR supports the National Academies of Sciences, Engineering and Medicine (NASEM) position suggesting more research is needed before appropriate risk and benefit standards are met for clinical trials.
“The ISSCR supports laboratory-based research that involves editing of the nuclear genomes of human sperm, eggs, or embryos, but that is only when it is performed under rigorous review and oversight, as suggested in our international guidelines,” said ISSCR president Doug Melton. “We do not support any clinical application of human germline or embryo editing at this time,” he said.