Amyloidosis, hereditary, transthyretin-related

Hereditary transthyretin (hATTR) amyloidosis can be known by lots of different names. This can be very confusing for individuals and families after they receive a diagnosis of this disorder. Some of the other names for hATTR amyloidosis include:

• ATTR, an abbreviation for hereditary transthyretin amyloidosis.
• Familial amyloid polyneuropathy (FAP), which refers to the neurological form affecting the nerves outside the central nervous system and the autonomic nervous system (which controls involuntary actions like sweating or maintaining blood pressure). Note: this is not to be confused with another genetic condition also abbreviated as FAP (familial adenomatous polyposis).
• Familial TTR amyloidosis, which refers to all forms.
• Hereditary transthyretin-related amyloidosis, which refers to all forms.
• Hereditary TTR-related amyloidosis, which refers to all forms.
• Transthyretin (TTR) amyloid polyneuropathy, which refers to the neurological form affecting the nerves outside the central nervous system and the autonomic nervous system (which controls involuntary actions like sweating or maintaining blood pressure).
• Transthyretin (TTR) cardiac amyloidosis, refers to the form that predominantly affects the heart.
• TTR amyloidosis with cardiomyopathy, refers to the form that predominantly affects the heart.
• TTR-FAP, an abbreviation for familial amyloid polyneuropathy.
• Leptomeningeal TTR amyloidosis, refers to the form that predominantly affects the central nervous system.

Some names for hereditary transthyretin amyloidosis are no longer commonly used. This includes: familial amyloid polyneuropathy type I (or the Portuguese-Swedish-Japanese type) and familial amyloid polyneuropathy type II (or the Indiana/Swiss or Maryland/German type).

There are different forms of hereditary transthyretin amyloidosis. This disorder is caused by changes (mutations) in the TTR gene. Different mutations can be associated with different symptoms or different forms.

hATTR amyloidosis with polyneuropathy is the most common form. People with this disorder may have problems with peripheral nerves (those outside of the central nervous system), and the autonomic nervous system, which controls involuntary actions of the body like sweating, blood pressure, and heart rate. Sometimes other symptoms can develop that affect the gastrointestinal system, the eyes, the heart and the kidneys.

hATTR amyloidosis with cardiomyopathy predominantly affects the heart. This can cause enlargement of the heart, irregular heart rhythms (arrhythmias), chest pain, congestive heart failure and potentially sudden death. Neurological involvement is either absent or very mild.

Leptomeningeal transthyretin amyloidosis affects the central nervous system and the brain. This form is extremely rare. People may have seizures, poor coordination (ataxia), stiffening of the muscles (spasticity), bleeding in the brain, psychosis, and dementia. Sometimes the eyes may be affected and this may be called oculoleptomeningeal transthyretin amyloidosis or familial oculoleptomeningeal transthyretin amyloidosis.

Hereditary transthyretin amyloidosis is the most common type of inherited amyloidosis. As of 2017, the overall worldwide prevalence of hereditary transthyretin amyloidosis is not known. However, it is a little more common in people from northern Portugal (estimated to be in 1 in 538 people of this background), Sweden, and Japan. Americans of European ancestry may have it less commonly, perhaps at a rate of 1 in 100,000 people. The form of hereditary transthyretin amyloidosis that significantly affects the heart (the cardiac form) is more common in people of African background, particularly from West Africa, and in Denmark.