Fast Five Quiz: How Much Do You Know About Amyloidosis?

Herbert S. Diamond, MD

Disclosures

November 02, 2018

Immunoglobulin light chain amyloidosis (AL) is the most common type of systemic amyloidosis in the United States, with an estimated 12,000 US adults currently living with the condition.

Outside of the United States, AA amyloidosis is more common than AL amyloidosis. The incidence of AA amyloidosis is also higher in developing countries, owing to the increased prevalence of infectious diseases associated with the condition.

AL amyloidosis is a monoclonal plasma cell disorder related to multiple myeloma (some patients with AL amyloidosis also meet diagnostic criteria for multiple myeloma) and monoclonal gammopathy of undetermined significance. Although AL amyloidosis can affect any organ, it most commonly affects the kidneys, heart, gastrointestinal tract, peripheral nervous system, and respiratory tract.

Abeta2M amyloidosis develops in patients with chronic renal failure, particularly those who have been on hemodialysis for a long time. In healthy patients, beta2m is cleaved from major histocompatibility complex in the kidneys; however, this clearance is impaired in patients with renal disease. Similarly, most hemodialysis machines cannot remove beta2m, though researchers are developing newer strategies to improve beta2m clearance.

Heavy-chain amyloidosis, when amyloid fibrils contain only heavy-chain immunoglobulins rather than light-chain immunoglobulins, is a rare form of amyloidosis. Heavy- and light-chain amyloidosis, in which amyloid deposits are from both heavy and light immunoglobulin chains, is also a rare form of amyloidosis.

Transthyretin (TTR), a protein produced primarily by the liver, transports plasma thyroxine and retinol. Two forms of ATTR exist: hereditary (familial) and wild-type. In both hereditary TTR amyloidosis (hATTR) and wild-type TTR amyloidosis (ATTRwt), TTR proteins accumulate into amyloid fibrils.

In patients with ATTRwt, TTR is normally sequenced, and the disease is often asymptomatic. ATTRwt most commonly affects the cardiac tissue of elderly patients, and is often only discovered postmortem on autopsy. In contrast, hATTR is caused by a mutated or faulty gene that often results in clinical signs and symptoms typically associated with fibril deposition in the nervous system and cardiac tissue.

For more on systemic amyloidoses, read here.

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