What is ATTR (transthyretin) amyloidosis?

What is ATTR (transthyretin) amyloidosis?

Transthyretin (trans-thigh-re-tin), also called TTR, is a protein made by the liver that helps carry thyroid hormone and vitamin A in the blood. Normally, TTR is made up of four identical parts. However, in ATTR amyloidosis, the protein becomes unstable, breaks apart, and deposits in the heart and/or the nerves.

There are two types of ATTR Amyloidosis:

Hereditary (familial) ATTR amyloidosis. In this form, there is a change (mutation) in the DNA that is inherited and can be passed from one generation to the next. This makes the TTR protein more unstable and more likely to form amyloid fibrils. Different mutations lead to different symptoms — some may affect the nerves; some may affect the heart; and some may affect both.

Wild-type ATTR amyloidosis. Unlike hereditary ATTR amyloidosis, wild-type does not involve abnormal DNA and cannot be passed on to family members. Instead, as you get older, the normal TTR protein becomes unstable, misfolds and forms amyloid fibrils.

These ATTR amyloid fibrils usually deposit in:

• The wrist, in a narrow pathway called the carpal tunnel. This can cause carpal tunnel syndrome, which causes your hand and arm to become numb and tingle.
• The spinal canal, which can cause narrowing of the spinal column (spinal stenosis).
• The heart, which can cause heart failure and/or an irregular heart rhythm called atrial fibrillation.
• Carpal tunnel syndrome and spinal stenosis can develop several years before heart failure.