Causes

There are many different types of amyloidosis. Some varieties are hereditary. Others are caused by outside factors, such as inflammatory diseases or long-term dialysis. Many types affect multiple organs, while others affect only one part of the body.

Subtypes of amyloidosis include:

• AL amyloidosis (immunoglobulin light chain amyloidosis). The most common type of amyloidosis in developed countries, AL amyloidosis is also called primary amyloidosis. It usually affects the heart, kidneys, liver and nerves.
• AA amyloidosis. Also known as secondary amyloidosis, this variety is usually triggered by an inflammatory disease, such as rheumatoid arthritis. Improved treatments for severe inflammatory conditions have resulted in a sharp decline in the number of cases of AA amyloidosis in developed countries. It most commonly affects the kidneys, liver and spleen.
• Hereditary amyloidosis (familial amyloidosis). This inherited disorder often affects the nerves, heart and kidneys. It most commonly happens when a protein made by your liver is abnormal. This protein is called transthyretin (TTR).
• Wild-type amyloidosis. This variety of amyloidosis occurs when the TTR protein made by the liver is normal but produces amyloid for unknown reasons. Formerly known as senile systemic amyloidosis, wild-type amyloidosis tends to affect men over age 70 and typically targets the heart. It can also cause carpal tunnel syndrome.
• Localized amyloidosis. This type of amyloidosis often has a better prognosis than the varieties that affect multiple organ systems. Typical sites for localized amyloidosis include the bladder, skin, throat or lungs. Correct diagnosis is important so that treatments that affect the entire body can be avoided.