They are the most thermodynamically stable structure that polypeptides can form, and require constant housekeeping to prevent. Accumulation of amyloids is like failing to taking out the trash in your house.

Afaik, there has never been a disease state checked for amyloids that failed to be associated with them (heart disease, cancer, stroke, etc).

>"From a wide range of in vitro experiments on peptides and proteins we now know that the formation of amyloid structures is not a rare phenomenon associated with a small number of diseases but rather that it reflects a well-defined structural form of the protein that is an alternative to the native state — a form that may in principle be adopted by many, if not all, polypeptide sequences

[...]

These observations, therefore, have led to the remarkable conclusion that, at the concentrations present in living systems, the native states may not always represent the absolute free energy minima of the corresponding polypeptide chains — the native form of a protein could in some cases simply be a metastable monomeric (or functionally oligomeric) state that is separated from its polymeric amyloid form by high kinetic barriers" http://www.ncbi.nlm.nih.gov/pubmed/24854788

I've previously commented the same thing:

https://news.ycombinator.com/item?id=14914528#14917057

https://hn.algolia.com/?query=amyloid%20nonbel&sort=byPopula...