[dnautics]

> What % is too human to harvest for organs

I don't think it's really measurable, because a meaningful "%" implies a relatively context-free, relatively uniformly distributed importance to genetic sequence.

The most immunogenic sugar is glycolylneuraminic acid. Humans are incapable of making this sugar so it's immediately recognizable as alien by the human immune system.

You could in theory disable production of this sugar with a single base pair mutation which (if that's how you did it) would make this .000001% sequence difference extremely important over almost any other sequence point.

As a side note it's a matter of speculation that the lack of this sugar is an evasion mechanism for species-jumping flu.

Edit: tick thing was wrong, I had misremembered! Thank you smart reader who has since deleted their comment calling me out.