This is a difficult question to answer, probably because it may challenge the 'spirit' of the law rather than the 'letter' of the law (i.e. halacha). Humans were given the cognitive capacity to create and use the environment around them as resources and tools, for greater good. In Bereishit (2:15) we are commanded to "work and guard" the land (i.e. the Garden of Eden). A number of mefarshim explain this in the broader context of taking responsibility for the resources around us, because no other animal has the capacity to do so... and we have the potential to be the most destructive!
That being said, Jewish scholarship has never abrogated from the use of medicine for the betterment of human wellbeing in general. We embrace it, insofar as it does not pose any specific halachic problem. There are few halachic objections to safe medical intervention after birth unless there is some fundamental halachic problem in using such an intervention (e.g. separating conjoined twins and debates about efficacy/safety of post-birth medication, etc.).
Safe gene editing aimed at reducing the risk of potentially hazardous/dangerous genetic diseases and syndromes seems easier to swallow, given that a person may take many preventative measures over his/her lifetime to prevent the likelihood of a health malady in any case (such as vaccinations and healthy lifestyle). We make these informed choices to reduce the risk of danger to our health.
The fundamental difference with gene editing is that, prior to birth, there are changes made to a human genome, which largely 'defines' who we are. This evokes feelings of 'playing God', and may seem wrong. Although, genes and gene expression are highly complex, on principle, removing the "Parkinson" gene and the Parkinson gene alone (for example, hypothetically) could very well be a desirable thing. "Natural" is not a virtue any more than malaria, typhoid, diabetes, arthritis and acne are natural. People will treat the symptoms of such conditions in any case; is that wrong?
Another reason this is difficult to talk about is because there are plenty people who live utterly fulfilling lives despite their condition (like Nick Vuhicic). There has also been a debate about whether screening for Down's syndrome is moral or desirable. All of these could be conceivably alleviated in the future through gene editing.
This is not intended to give a 'hard' answer to the OP's question but that although it may seem not to go against any fundamental halachic issue there is a more broad issue that needs addressing that encompasses the 'spirit of the law'.
Alleviating direct suffering is an easier case to make for gene editing, despite numerous people living fulfilling lives despite their conditions. A more challenging question is 'how far could people be willing to take this' i.e. 'designer babies'. I would read Aldous Huxleys 'A Brave New World' for a stark dystopian perspective.
See Rabbi Sacks in this video (minute 27+), who makes a distinction between theraputic and eugenic genetic intervention.
