The Kuna carry a congentital neurodegenerative disease called Gelsir that affects only a few individuals in thousands. Every Kuna carry the disease, but only a few ever develop the symptoms and enter the gelsir state.   A Kuna who goes into the gelsir state is no longer called a Kuna. They are instead refered to as a Gelsir or a Gelsir Kuna, which is an old word meaning "Rage" or "Fury". A Kuna in the early stages of Gelsir will display increased aggression, short temper and violent outbursts. An increase in salivation give them a constant drooling and their posture will become increasingly hunched over.   A full Gelsir outbreak will strip the Kuna of their mental faculties completely and they will revert to a violent, aggressive state where they attack attack everyone in the hunt for food. They will have no qualms about eating the flesh of other races in this state. They cannot be reasoned with and they will attack any non-Kuna, and in some cases even non-Gelsir Kuna will be attacked.   As player characters
Every year past the age of 20, you must make a check against this trait. The difficulty increases by 1 for every five years past 20. So if you are 28, you make a yearly check against 2. If the check fails, you will begin to develop early Gelsir symptoms. Remove this trait from your character sheet and replace it with the Gelsir [CotC] trait at -1. If the check was a fumble, you add Gelsir [CotC] at -2.   The yearly Gelsir check is subject to Hero Points.