The term relapse refers to the loss of sentience, turning Gestalts hostile and aggressive, leading them to even attack Replicants.
Ordinarily, all Gestalts that were created immediately relapsed. Thanks to the discovery of the Original Gestalt and the distribution of his maso, other Gestalts can assume a stabilized state. This would later be an inaccurate assumption due to the Original Gestalt's corrupted DNA and a bug in Project Gestalt.
The corruption appears to only affect a conscious soul, so the effects can be paused through cold sleep.
If a Replicant is created from a relapsed Gestalt, they will inevitably be affected by the Black Scrawl. Once a Gestalt has relapsed, they can never return to their Replicant.
Following the death of the Original Gestalt, all Gestalts began to relapse and die out with Replicants soon following them. Because of this, Humanity eventually went extinct with the exception of Emil.