These technologies have strong potential for therapeutic gene therapy, although it must be said that their application in humans, particularly human embryos, raises considerable ethical questions. Theoretically speaking, in the case of gene duplications that lead to developmental disorders, corrective gene therapy applied at an early developmental stage might potentially prevent, to some extent, the development abnormalities caused by high levels of a protein (in this case MECP2). Also theoretically, post-natal gene editing might have positive effects in these cases, for example if the disease phenotype is being permanently reinforced after birth by the duplication. But it's very early days for the technology and its application in humans are still only starting to be explored.

These genome editing technologies have the capacity for gene deletion, but its application in humans, particularly human embryos, raises considerable ethical questions. Because of the relatively novelty of this technology these questions are only just starting to be debated, although there are already a handful of studies of genome editing in humans reported in the literature.

It's great to see a live collaborative spirit in this highly dynamic research area.

For further reading on the topic, see this feature article by David Owen, staff writer at The New Yorker: http://www.newyorker.com/magazine/2017/04/03/high-tech-hope-for-the-hard-of-hearing