The International Society for Stem Cell Research released a statement that called for a moratorium nuclear genome editing of the human germ line to give scientists more time to analyze the potential risks associated with the practice as well as discuss the ethical principles involved.

These technologies could allow researchers to introduce changes into the DNA sequence of cells extremely quickly. This means genome editing can be performed not only on adult cells, but in embryos and gametes as well; these early cells carry inheritably germline DNA. Research on this type of genome editing has already been performed on mice and monkeys, and could be applied to humans in the future.

"The ISSCR statement raises significant ethical, societal and safety considerations related to the application of nuclear genome editing to the human germ line in clinical practice. Current genome editing technologies carry risks of unintended genome damage, in addition to unknown consequences. Moreover, consensus is lacking on what, if any, therapeutic applications of germ line genome modification might be permissible," the Society stated.

The statement calls for a halt of all attempts to apply nuclear genome editing of the human germ line in clinical practices until adequate research has been performed and the long-term risks have been assessed.

"The ISSCR asserts that a deeper and more rigorous deliberation on the ethical, legal and societal implications of any attempts at modifying the human germ line is essential if its clinical practice is ever to be sanctioned," the Society stated.

The ISSCR noted it is not taking a position on clinical testing of mitochondrial replacement therapy, in which mitochondria in the eggs of women at risk of transiting certain diseases are altered through germline modification.