Can a human survive without ACE2?
No obviously inactivating variants are found in this gene, which provides at least negative data (humans generally seem to have at least somewhat functional ACE2). Exome sequencing across &gt;200K humans has found a series of variants, mostly low-frequency, in the population.
Some of these variants may affect gene function, but it is not clear how, and none of them are obviously complete loss of function variants (e.g. nonsense mutations).
A more complete analysis of the data, including e.g. CNVs, might be necessary to fully address this question.