Hereditary ATTR (hATTR) amyloidosis is a rare, genetic condition that affects an estimated 50,000 people worldwide. It is caused by a gene change, or mutation, that affects the function of a protein called transthyretin (TTR). In hATTR amyloidosis, the TTR gene mutation causes the protein to take on an abnormal shape and misfold, which causes the protein to build up in various parts of the body, including the nerves, heart, and digestive system. This build-up of proteins, also called amyloid deposits, causes the symptoms of hATTR amyloidosis.

Although anyone can be at risk for this disease, it is more common in certain ethnicities, including people of African, Irish, and Portuguese descent. It is estimated that approximately 1 in 25 (4%) African Americans have a certain TTR gene mutation associated with hATTR amyloidosis.

Symptoms of hATTR amyloidosis can be very different from person to person and can affect some parts of the body more than others. Some symptoms a person with hATTR amyloidosis may experience include:

  • Tingling and/or numbness in the hands and feet
  • Carpal tunnel syndrome in both hands
  • Dizziness upon standing
  • Shortness of breath
  • Diarrhea or constipation
  • Unexplained weight loss
  • Nausea and vomiting
  • Sexual dysfunction
  • Kidney dysfunction
  • Weakness
  • Burning pain
  • Loss of sensitivity to temperature

This is not a complete list of symptoms that may be experienced in patients with hATTR amyloidosis. Each patient has a different experience and you may not experience all of these symptoms, or you may not experience them at the same time.

hATTR amyloidosis is passed down through family members. If one parent has hATTR amyloidosis, each child will have a 50% chance of inheriting a mutation that may cause this condition. A family member may inherit the TTR gene mutation, but that does not necessarily mean he or she will develop hATTR amyloidosis.

Educating yourself and your loved ones about the symptoms of this condition can help you identify them if they occur. Symptoms may worsen over time, so it’s important to talk to your doctor to determine the right plan of action. This may include referring you to a doctor with more experience with hATTR amyloidosis or recommending you work with a genetic counselor. A genetic counselor can help you learn more about the genetic testing process and if a genetic test may be right for you.

You and your family can also learn more about hATTR amyloidosis from Alnylam Patient Education Liaisons (PELs), who are professionals with backgrounds in nursing or genetic counseling and who can answer questions and provide helpful resources about this condition.

Visit for more information about hATTR amyloidosis and visit to connect with a PEL.

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