| You misunderstand so many things. 1. There are many somatic applications of CRISPR that have no effect on the germline. 2. Even the germline applications don't necessarily "decrease genetic variability". Why would you think that? 3. Even considering off-target effects, the edits made to any particular genome are miniscule compared to its overall size, which I'm sure would astound you. There is no reason to believe these edits will make us less (or more) resistant to environmental exposures. 4. We are not talking making people more likely to contract cholera, which is easily controlled by sanitation. We're talking about preventing or curing debilitating illnesses that confer no benefit to the organism. |
https://www.cdc.gov/malaria/about/biology/sickle_cell.html
I would think that a mendelian genetic disease like sickle cell might well be on our hit list for all the trouble it causes. Of course, it could be argued that mosquito nets and drugs (i.e. technology) are a better, less costly defense, than these inborn genetic mutations.