Amyloidosis is the collective name for a group of diseases characterized by the deposition of amyloids—insoluble proteins that form due to the misfolding and aggregation of soluble proteins—outside of cells. Such depositions lead to cellular dysfunctions, and take place in patients with Alzheimer's disease, Parkinson's disease and dementia. In the disease called hereditary (variant) transthyretin amyloidosis (abbreviated ATTRv amyloidosis), variants of the transthyretin (TTR) gene lead to TTR amyloid deposits in several organs, with symptoms including muscle weakness and cardiac failure.