What if you test positive for a TTR mutation but have no symptoms?
Fact-checked by You feel fine, but your genetic test results show you carry a transthyretin (TTR) mutation. What’s next? For some people, learning they have a TTR mutation but no symptoms can bring more questions than answers.
A positive test result doesn’t necessarily mean you will develop hereditary transthyretin amyloidosis with polyneuropathy (hATTR-PN).
However, you may need to plan for further monitoring and testing, and you may want to learn more about your personal risk.
What a positive TTR genetic test means
A positive hATTR-PN genetic test means you have a change, or variant, in your TTR gene. This gene helps your body make transthyretin, a protein that carries certain substances in the blood.
Transthyretin exists in a stable tetramer structure containing four individual proteins. In inherited forms of amyloidosis, including hATTR-PN, some TTR variants can prevent transthyretin from forming tetramers, leaving individual proteins prone to misfolding or adopting the wrong shape. As a result, they can build up as abnormal protein clumps (amyloid deposits) in nerves, the heart, and other organs.
Not everyone who’s a TTR mutation carrier will develop hATTR-PN. The likelihood of developing symptoms, called penetrance, varies widely depending on the specific TTR mutation, geographic background, and age.
For example, studies of people carrying the common Val30Met mutation have shown that penetrance ranges from 22% at age 60 to 69% at age 90 in some Swedish populations. Among Portuguese carriers of the same mutation, however, about 89% develop symptoms by age 60 and 91% by age 80. This means that while some carriers are very likely to eventually develop hATTR-PN, others may never experience symptoms despite having the mutation.
Because risk varies widely from person to person, your results are best interpreted with the help of a doctor or genetic counselor.
Can you have a mutation and still feel completely well?
Yes, you can be an asymptomatic TTR mutation carrier, meaning you have the mutation but feel completely normal. You may also hear the term presymptomatic hATTR-PN. This is sometimes used when your care team is monitoring for possible early signs of disease based on your mutation, age, family history, or test results. However, it doesn’t mean symptoms are certain to occur.
How doctors monitor people before symptoms begin
After a positive test result, your care team may recommend hATTR-PN surveillance. This involves regular checkups to look for early signs of disease before noticeable symptoms appear. Because current treatments are approved for people who have symptoms, identifying disease onset as early as possible may allow you to begin treatment sooner, when it is generally most effective.
Because early signs can be subtle, follow-up may focus on monitoring these areas of your health:
- Nerve health: Exams or tests that check feeling, pain, strength, reflexes, and balance
- Autonomic body functions: For example, dizziness when standing, digestion, sweating, bladder changes, or sexual function
- Heart health: Electrocardiogram, echocardiogram, or blood tests that look for heart strain
- Kidney health: Urine or blood tests that look for early kidney changes
Asymptomatic carriers may be seen once per year, while people with possible early changes may be checked every three to six months. Early monitoring allows your doctor to establish a baseline and watch for meaningful changes over time.
What this means for family members
Because hATTR-PN is inherited, a positive TTR genetic test result may have implications for close relatives. The condition follows an autosomal dominant pattern, meaning a child, parent, or sibling of someone diagnosed with hATTR-PN has a 50% chance of carrying the same mutation.
Family screening for hATTR-PN can help relatives learn whether they also carry the mutation. A genetic counselor can guide you through deciding who to tell, how to explain the result, and where relatives can ask about testing.
When to see a genetic counselor
You might consider meeting with a genetic counselor soon after getting a positive test result. They can explain what your specific TTR variant may mean, review the limits of testing in predicting outcomes, and help you prepare for future care decisions.
Genetic counseling can also include help with emotional, practical, and family-planning questions that may arise when learning your result before symptoms begin. It can be especially helpful if you’re unsure how much information you want or how to make choices without feeling rushed.
Questions to ask after receiving your results
A positive test result can be easier to process when you leave your appointment with clear next steps. Because follow-up may depend on your age, mutation status, family history, and early test results, it may help to bring a list of questions.
Consider asking the following questions:
- What TTR variant do I have, and what is known about it?
- When should monitoring begin, and how often should I be checked?
- Which symptoms should be reported between visits?
- Which specialists should be part of my care team?
- What should I share with relatives who may want to be tested?
You may also request a written summary of your results, which can help you feel better prepared and supported as you plan your next steps.
Your care team or genetic counselor can help you decide which monitoring approach is appropriate for your situation.
Amyloidosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
