Do not overlook the possibility of genome-edited somatic cells ending up in the human germline

Most debates on human germline genome editing have limited discussions to just genetic modifications of sperm and eggs (gametes), their precursors within testicular or ovarian tissues, and preimplantation human embryos. What has largely been overlooked is that genome editing of somatic (non-reproductive) cells can also become heritable and can potentially be transmitted to future generations of human offspring under specific experimental conditions, due to the emergence of various new technology platforms. Most notably, the reprogramming of human somatic cells to a pluripotent “embryonic stem cell-like” state (i.e. induced pluripotent stem cells), has opened up the possibility that genome editing performed on human somatic cells can also be transmitted to future generations of human offspring when combined with other new technology platforms, such as in vitro gametogenesis, chimeric and synthetic embryos. Additionally, due to high levels of plasticity and extensive tissue remodeling within the human fetus during gestation, it is speculated that genome editing performed on fetal somatic cells intended for fetal gene therapy in utero may be unintentionally transmitted to the human germline. Hence, there should be strict regulatory oversight to ensure that any genome-edited somatic cell that ends up in the human germline via such aforementioned technology platforms does so in strict compliance with relevant legislation and ethical guidelines, especially that pertaining to safety issues with genome editing technology and its potential misuse in human enhancement and eugenics.