Survival time is not associated with gender or age, however, some measures of reduced heart function are associated with a shorter survival time.Senile systemic amyloidosis was determined to be the primary cause of death for 70% of people over 110 who have been autopsied. Epidemiology
Amyloidosis has a combined estimated prevalence of 30 per 100,000 persons with the three most common forms being AL, ATTR, and AA. The median age at diagnosis is 64.AL has the highest incidence at approximately 12 cases per million persons per year and an estimated prevalence of 30,000 to 45,000 cases in the US and European Union.AA amyloidoses is the most common form in developing countries and can complicate longstanding infections with tuberculosis, osteomyelitis, and bronchiectesis. AA amyloidosis is caused by an increase in extracellular deposition of serum amyloid A (SAA) protein. SAA protein levels can rise in both direct and indirect manners, through infection, inflammation, and malignancies. The most common causes of AA amyloidosis in the West are rheumatoid arthritis, inflammatory bowel disease, psoriasis, and familial Mediterranean fever.People undergoing long-term hemodialysis (14–15 years) can develop amyloidosis from accumulation of light chains of the HLA 1 complex which is normally filtered out by the kidneys.Wild-type transthyretin (ATTR) amyloidosis is found in a quarter of elderly at postmortem. ATTR is found in 13-19% of people experiencing heart failure with preserved ejection fraction, making it a very common form of systemic amyloidosis.
Twenty percent of people with AL amyloidosis have an enlarged tongue, that can lead to obstructive sleep apnea, difficulty swallowing, and altered taste. Tongue enlargement does not occur in ATTR or AA amyloidosis. Deposition of amyloid in the throat can cause hoarseness. Pathogenesis
Amyloidoses can be considered protein misfolding diseases. The vast majority of proteins that have been found to form amyloid deposits are secreted proteins, so the misfolding and formation of amyloid occurs outside cells, in the extracellular space. Of the 37 proteins so far identified as being vulnerable to amyloid formation, only four are cytosolic. Most amyloid-forming proteins are relatively small, but otherwise there is currently no evidence of structural or functional similarities among proteins known to form disease-associated amyloids. One third of amyloid disease is hereditary, in which case there is normally an early age of onset. Half of amyloid-related diseases are sporadic and have a late age of onset – in these cases, the protein aggregation may be associated with aging-related decline in protein regulation. Rarely, some medical treatments are associated with amyloid disease.Amyloid-forming proteins aggregate into distinctive fibrillar forms with a beta-sheet structure. The beta-sheet form of amyloid is proteolysis-resistant, meaning it can not be degraded or broken down. As a result, amyloid deposits into the bodys extracellular space. The process of forming amyloid fibrils is thought to have intermediate oligomeric forms. Both the oligomers and amyloid fibrils can be toxic to cells and can interfere with proper organ function.