Genetic testing for hATTR-PN
Reviewed by Hereditary transthyretin amyloidosis with polyneuropathy (hATTR-PN) can resemble other forms of neuropathy, especially when symptoms develop slowly or are similar to those of more common conditions. This can make it harder to diagnose. Genetic testing looks for disease-causing variants in the TTR gene. It can help confirm that ATTR amyloidosis is hereditary when symptoms resemble those of other neuropathies.
Finding a disease-causing (pathogenic) TTR variant can confirm that a person carries the genetic cause of hereditary transthyretin amyloidosis. However, the result must be considered alongside symptoms and other medical findings. Carrying a disease-causing TTR variant does not necessarily mean someone has developed hATTR-PN.
Testing can also help guide diagnosis, genetic counseling, testing for family members, and monitoring for signs of disease. Treatments that target the disease include gene-silencing therapies and other transthyretin-targeted treatments. The choice of treatment depends on a person’s symptoms, other clinical findings, and treatment goals.
The role of genetic testing in confirming hATTR-PN
Genetic testing for hATTR-PN looks for disease-causing variants in the TTR gene using DNA from blood, saliva, or a cheek swab. Finding a disease-causing (pathogenic) variant can confirm that ATTR amyloidosis is hereditary. Along with symptoms and other medical findings, the result can help clarify an hATTR-PN diagnosis.
The TTR gene provides instructions for making transthyretin. Disease-causing TTR variants can change the protein’s shape, leading to amyloid deposits that can affect nerves, the heart, and other organs.
A 2024 U.S. expert panel recommends genetic testing when hereditary ATTR is suspected. Because hATTR-PN can resemble other forms of nerve damage, including diabetic neuropathy, diagnosis may be delayed. Doctors must consider genetic test results alongside symptoms and other medical findings to determine whether hATTR-PN is causing the nerve damage.
When a disease-causing TTR variant is found, doctors look for signs of progressive nerve damage, problems with automatic body functions, and other findings that may point to hATTR-PN. Genetic testing can also help distinguish hereditary ATTR from wild-type ATTR, which is not caused by a disease-causing TTR variant.
One well-known disease-causing TTR variant was previously called Val30Met but is now called p.Val50Met because of changes in how the protein is numbered. Both names refer to the same genetic variant.
Not everyone who inherits a disease-causing TTR variant develops symptoms.
This is known as incomplete penetrance, which means not everyone who carries the variant develops the disease. Among those who develop symptoms, the age when symptoms begin and how severe they become can vary widely, even within the same family.
Types of genetic tests and sample collection methods
The type of genetic test used for hATTR-PN can depend on whether a disease-causing TTR variant is already known in the family.
There are several ways to test for hereditary ATTR:
- TTR gene sequencing: This test looks for disease-causing variants in the TTR gene and may be used when no family variant is known.
- Targeted family variant testing: If a disease-causing TTR variant is already known in the family, this test can show whether other relatives carry it.
- Multigene panel testing: This test looks at TTR and other genes linked to inherited nerve disorders or related conditions. A doctor may recommend it when symptoms could be caused by several genetic conditions and the cause is unclear.
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| Test type | Who may need the test | Sample method | Why the test is used |
|---|---|---|---|
| TTR gene sequencing | People with suspected hereditary ATTR when no family variant is known | Blood, saliva, or cheek swab | Identify a disease-causing TTR variant |
| Targeted family variant test | Relatives of someone with a known disease-causing TTR variant | Blood, saliva, or cheek swab | Find out whether a relative inherited the family’s specific variant |
| Multigene panel | People with unexplained nerve damage that may have several inherited causes | Blood, saliva, or cheek swab | Check TTR and other genes that may explain the symptoms and medical findings |
DNA for genetic testing may be collected from blood, saliva, or a cheek swab. One hATTR genetic testing program offers an at-home specimen collection option.
A variant of uncertain significance (VUS) means a genetic change was found, but available evidence does not yet show whether it causes disease. A VUS does not mean a person has hATTR-PN and does not confirm or rule out the condition. Results should be reviewed with a doctor or genetic counselor. Over time, a VUS may be reclassified as more scientific and medical evidence becomes available.
Genetic counseling and family cascade testing
hATTR-PN is inherited in an autosomal dominant pattern. This means a person with one copy of a disease-causing (pathogenic) TTR variant has a 50% chance of passing it to each biological child. However, inheriting the variant does not mean symptoms will definitely develop. The chance of developing the disease and the age when symptoms begin can vary between families and depending on the specific TTR variant.
Genetic counseling for hATTR-PN can help people understand test results, review family history, consider how results may affect family planning, and discuss the emotional concerns and uncertainties of testing.
In the U.S., the Genetic Information Nondiscrimination Act (GINA) provides protections against the use of genetic information in health insurance and employment decisions. These protections generally do not apply to life insurance, disability insurance, or long-term care insurance. A genetic counselor can help explain how these protections and limitations may apply to a person’s situation.
Once a disease-causing TTR variant is confirmed in a family, other relatives who may have inherited it can be offered genetic testing, known as cascade testing. Close relatives, including parents, siblings, and biological children, may be among those considered for testing.
A 2026 study found that family genetic screening identified people carrying TTR variants, including those with and without symptoms. The findings support earlier diagnosis, regular monitoring, and access to treatment when disease develops.
Predictive testing of relatives is different from testing someone who already has symptoms. A person who carries an hATTR-PN-associated variant but has no symptoms is at risk of developing hereditary ATTR. However, carrying the variant does not mean the person has active disease. Decisions about predictive testing in relatives without symptoms are best made in consultation with a genetic counselor and may depend on age, family history, and personal preferences.
For people who develop symptomatic hATTR-PN, identifying a pathogenic TTR variant can help confirm the hereditary cause and support timely treatment decisions. Learning that a person carries a disease-causing TTR variant may also cause uncertainty or anxiety, which is one reason genetic counseling is recommended before and after testing.
How genetic results guide early treatment and disease monitoring
Early diagnosis of hATTR polyneuropathy is important because starting treatment earlier is linked to better outcomes.
A positive TTR genetic test can help confirm that ATTR amyloidosis is hereditary. However, treatment is generally started when a person develops symptoms, not simply because they carry a disease-causing TTR variant.
Several approved therapies target transthyretin through different mechanisms. For adults with symptomatic hATTR-PN, treatments that reduce transthyretin production include Amvuttra (vutrisiran), Onpattro (patisiran), and Wainua (eplontersen).
For people who carry a disease-causing TTR variant but do not yet have symptoms, experts recommend an initial health assessment several years before symptoms would be expected based on their family history or specific variant. This assessment gives doctors a starting point for tracking changes over time. Monitoring may include checking for early hATTR-PN symptoms, nerve and heart involvement, and other signs of ATTR disease. [repeated source]
How often follow-up visits are needed can vary based on the specific variant, family history, expected age when symptoms may begin, and medical findings.
Monitoring nerve health may include reviewing symptoms, checking nerve function during an examination, and assessing automatic body functions, such as heart rate and digestion. Nerve conduction studies and electromyography (EMG), which assess how nerves and muscles work, may be used when needed.
Monitoring can also include heart tests and checks for problems affecting automatic body functions or other organs. Changes from the initial assessment may lead to more testing to see whether symptoms of the disease have begun.
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