The news buzz alive with excitement about human genome editing, even human germline engineering. Successful germline engineering requires (1) a technology for editing DNA safely and (2) knowledge of what to edit and how to edit based on understanding the underlying biology. We are approaching (1), which is the easier part; we do not have (2), and we are far from achieving it for most desired “edits”.

A huge hurdle to germline engineering is that, beyond a few simple cases, our understanding does not allow achieving desired effects while avoiding unintended consequences. Unlike DNA sequencing, silicon chips and DNA editing, our understanding of complex combinatorial multi-gene interactions has made very little progress over the last few decades. Until we made more progress and understand gene interactions and the respective health outcomes better, germline engineering is akin to medieval quack therapies based the technology to bleed patients and feed them various concoctions but with very limited understanding of the medical consequences, and with plenty of unintended consequences. We can fix the unintended consequences later and then fix the unintended consequences from the fixing, and we will keep trying!