Leo, living with hATTR amyloidosis


Understanding Hereditary ATTR Amyloidosis

Hereditary ATTR (hATTR) amyloidosis is an inherited, progressive disease caused by a genetic mutation that results in the misfolding of transthyretin (TTR) proteins. This results in the formation of amyloid fibrils that could deposit in the nerves, heart, and/or gastrointestinal (GI) tract.

hATTR amyloidosis affects approximately 50,000 people worldwide. Many people remain undiagnosed or misdiagnosed and treatment options for people with this disease are limited.

How does hATTR amyloidosis affect the body?

People with hATTR amyloidosis have a genetic mutation that prevents TTR protein, which is made in the liver, from having its normal structure. Instead, TTR misfolds and accumulates as amyloid deposits in the body—in the heart, nerves, and GI tract, as well as other organs—causing debilitating symptoms.

Symptoms associated with this condition

hATTR amyloidosis symptoms can vary from person to person, depending on which organs or tissues are affected, and can worsen as the disease progresses. Symptoms may include:

  • Loss of sensation, limb weakness and pain
  • Alternating episodes of diarrhea, constipation, nausea, and vomiting
  • Heart-related issues
  • Eye, kidney, and thyroid disease


For a complete list of symptoms, see the hATTR amyloidosis Backgrounder below.

Learn more about hATTR amyloidosis

Download the Alnylam hATTR amyloidosis Backgrounder.

Meet Leo

“I knew the symptoms. I knew the signs—but I never thought it would get me.”

This is Leo’s story about living with hATTR amyloidosis.

From Possibility to Patients


The Bridge is a program designed to help raise awareness of hereditary ATTR (hATTR) amyloidosis and promote education on the condition for patients and their families.

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Alnylam Act provides no-charge, independent genetic testing and counseling to individuals in the US who may have hATTR amyloidosis.

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Learn about one family’s journey living with hATTR amyloidosis.

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At Alnylam, we put you at the center of everything we do. We have a team dedicated to collaborating with patient advocacy groups and individuals affected by these rare diseases.

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