> It has been observed (in mice) that editing the germline by directly editing the embryo will result in chimerism in the fetus. This is an implementation deta

> It has been observed (in mice) that editing the germline by directly editing the embryo will result in chimerism in the fetus. This is an implementation detail to be overcome, not a problem with the general concept. And this study seems to have overcome it. > The earlier Chinese publications, although limited in scope, found CRISPR caused editing errors and that the desired DNA changes were taken up not by all the cells of an embryo, only some. That effect, called mosaicism, lent weight to arguments that germline editing would be an unsafe way to create a person. > But Mitalipov and his colleagues are said to have convincingly shown that it is possible to avoid both mosaicism and “off-target” effects, as the CRISPR errors are known.