Amyloidosis is a group of conditions caused by the buildup of amyloid fibrils in the body. Each type is caused by a different misfolded protein. This article discusses hereditary ATTR (hATTR) amyloidosis, a rare form of the condition, which affects roughly 50,000 people globally.
What is hATTR amyloidosis?
hATTR amyloidosis is caused by a genetic mutation that affects the function of a protein in the blood called transthyretin (TTR). The TTR protein, made primarily in the liver, occurs naturally in most people to help carry substances the body needs, such as vitamin A. But when someone has a TTR mutation, the protein can misfold or take on an abnormal shape. This abnormality causes the protein to clump together and build up as amyloid deposits in the nervous, cardiac, and digestive systems.
How is hATTR amyloidosis inherited?
hATTR amyloidosis can be passed down from generation to generation, so it’s important to understand how this happens. Genes are located on structures known as chromosomes. Everybody has two copies of the TTR gene, one inherited from each parent. The condition is inherited in an autosomal dominant fashion, meaning if one parent has hATTR amyloidosis, each child will have a 50% chance of inheriting a genetic mutation that may cause this condition. It’s also important to note that a family member may inherit the TTR gene with a mutation but having the mutation does not necessarily mean he or she will develop hATTR amyloidosis.
What are the symptoms of hATTR amyloidosis?
Misdiagnosis is common with hATTR amyloidosis because the symptoms can resemble those of other conditions. Learning about the symptoms of hATTR amyloidosis can help you identify them if they occur and prompt a discussion with your healthcare professional. People with hATTR amyloidosis can have a variety of symptoms. In fact, symptoms can differ widely among people with the same mutation and sometimes even within families. Different symptoms may appear at different times for everyone, and the age of onset of initial symptoms may vary, ranging from the mid-20s to the mid-60s.
Symptoms may include:
What should you do if you experience hATTR amyloidosis symptoms?
If you experience symptoms associated with hATTR amyloidosis, talk to your healthcare professional. Specifically, speak with a specialist familiar with hATTR amyloidosis, such as a neurologist or cardiologist, depending on your symptoms, to determine if you may be at risk for developing the condition. If you haven’t experienced symptoms but you know there’s a family history, your healthcare professional can refer you to a genetic counselor. Genetic counseling can help you understand your chances of inheriting the condition as well as familiarize you with the testing process and implications of a diagnosis. Genetic counselors also can explain the issues related to genetic testing—from personal risk to possible insurance impact—and can help you determine if a genetic test is right for you.
How is hATTR amyloidosis treated?
There are treatments available that address the underlying cause of hATTR amyloidosis by decreasing the amount of TTR protein that’s made in the body. There are also treatments that bind to TTR proteins and help them from forming deposits. Liver and/or heart transplants are also an option for some patients who meet certain eligibility criteria.
Due to the progressive nature of hATTR amyloidosis, managing symptoms is an ongoing process. Physicians may prescribe medications to treat some of these symptoms and reduce the daily impact they may have. Additional treatment options for hATTR amyloidosis are currently being researched.
Learn more about hATTR amyloidosis at Alnylam’s THE BRIDGE®: hATTRbridge.com
For additional information and assistance, try these resources:
- Amyloidosis Foundation: amyloidosis.org
- Amyloidosis Support Groups: amyloidosissupport.org
- Amyloidosis Research Consortium: arci.org
- National Organization for Rare Disorders: rarediseases.org
- Global Genes: globalgenes.org