With certainty, there are numerous aspects of known unknown, as well as unknown unknowns when it comes to CRISPR. Aside from the off-target effect discussed previously, there are also on-target but unexpected and deleterious effects, as described in a news story by Columbia University Medical Center (CUMC). To correct a gene that gives rise to congenial blindness, scientists at CUMC and collaborating research institutes edited the culprit gene using CRISPR/Cas9 in human embryos. To the surprise of many, the CRISPR/Cas-edited gene of interest caused a tempestuous storm in the cells so severe that it led to the destruction of either the entire chromosome of which the edited gene is a part or large sections of the chromosome.40
Science aside, the question must be asked: Is CRISPR/Cas9 human embryo editing banned in the United States? Indeed, as we discussed previously, the ban in the US is a fact but conditional. At this point, the ban in the US is government-funded CRISPR/Cas9 research in human embryos, excluding similar research sponsored by private funds. As described in the disclaimer by CUMC, the human embryos were obtained from a New York-based reliable stem cell center, and the research funds were provided privately.
As the CRISPR system becomes more optimal, especially in more rational guide RNA designs and more feasible delivery routes, its application in biomedical therapeutics of nongermline, nonhuman embryo realms will become a more formidable gene-editing tool to correct severe medical disorder-causing faulty genes. Time will tell if and how this progress is made.
