hATTR Amyloidosis: Effects on Nerves and Heart

hATTR amyloidosis, also called hereditary or variant transthyretin amyloidosis (ATTRv), is a genetic condition caused by changes in the TTR gene. These changes can lead to abnormal protein deposits that gradually affect the nerves, heart, digestive system, eyes, or kidneys; early specialist assessment can help guide monitoring and treatment.

Overview: What Is hATTR Amyloidosis?

hATTR amyloidosis is a rare inherited condition in which a changed transthyretin (TTR) protein becomes unstable and can form amyloid deposits. Transthyretin is made mainly in the liver and normally carries thyroid hormone and vitamin A in the bloodstream. In hATTR amyloidosis, deposits may build up over time in tissues, especially peripheral nerves and the heart.

The condition is also known as hereditary transthyretin-mediated amyloidosis, hereditary ATTR amyloidosis, or ATTRv amyloidosis. The letter “h” refers to hereditary, while “v” refers to a genetic variant. It is different from wild-type ATTR amyloidosis, which is not inherited and tends to occur later in life.

hATTR amyloidosis can be serious, but its course differs greatly between people. The type of TTR variant, age at symptom onset, organs involved, and access to timely care all influence the outlook. Treatments and coordinated specialist follow-up have expanded considerably, making an accurate diagnosis especially important.

How hATTR Amyloidosis Can Affect the Body

Amyloid deposits can interfere with the normal function of nerves, the heart, and other organs. Some people mainly develop polyneuropathy, meaning damage to nerves outside the brain and spinal cord. Others have predominantly cardiac disease, and many have a combination of nerve and heart involvement.

Peripheral nerve involvement often begins in the feet and lower legs, then may progress upward. Autonomic nerves, which regulate automatic body functions such as blood pressure, sweating, bowel movements, and bladder function, can also be affected. This explains why symptoms may seem unrelated at first.

When deposits affect the heart muscle, the walls may become stiff and less able to relax and fill normally. This can lead to a form of heart failure in which fluid retention, tiredness, or breathlessness occur despite a preserved pumping percentage on some tests. Amyloid can also affect the heart’s electrical system and cause rhythm or conduction problems.

Less commonly, hATTR amyloidosis may affect the eyes, kidneys, or tissues around the brain and spinal cord. A person’s care plan is therefore based not only on the genetic result, but also on a careful assessment of the organs involved.

Symptoms of hATTR Amyloidosis

Symptoms usually develop gradually and can be mistaken for more common conditions, including diabetes-related neuropathy, spinal problems, irritable bowel symptoms, or heart disease. The pattern is variable: symptoms may begin in adulthood, although the age of onset can differ even among relatives with the same TTR variant.

Nerve-related symptoms may include burning, tingling, numbness, shooting pain, reduced temperature sensation, muscle weakness, balance difficulties, or problems walking. Symptoms often start in the feet. Some people may develop carpal tunnel syndrome, particularly if the wrists are affected before more widespread symptoms become clear.

Autonomic symptoms can include light-headedness or fainting when standing, constipation or diarrhea, nausea, early fullness after meals, unintentional weight loss, changes in sweating, erectile dysfunction, or difficulty emptying the bladder. These symptoms should be discussed openly with a clinician, as they can often be managed.

Possible cardiac symptoms include shortness of breath during activity, swelling of the ankles or abdomen, fatigue, palpitations, dizziness, or reduced exercise tolerance. Not everyone with hATTR amyloidosis has all of these symptoms, and their presence does not by itself confirm the diagnosis.

• Progressive numbness, pain, or weakness in the feet and hands
• Dizziness on standing or episodes of fainting
• Persistent bowel, bladder, or sexual-function changes alongside nerve symptoms
• Breathlessness, swelling, palpitations, or unexplained thickening of the heart muscle

Causes and Inheritance

hATTR amyloidosis is caused by a disease-associated variant in the TTR gene. This gene provides instructions for making transthyretin. More than one genetic variant can lead to hATTR amyloidosis, and different variants are associated with different patterns of nerve, heart, eye, or other organ involvement.

The condition is usually inherited in an autosomal dominant pattern. This means that a person with a TTR variant has a 50% chance of passing that variant to each child, regardless of the child’s sex. However, inheriting a variant does not reliably predict when symptoms will begin, how severe they will be, or which organs will be affected.

Some people are diagnosed because a relative has hATTR amyloidosis. Others have no known family history, which can happen when prior generations were not diagnosed, developed symptoms later in life, had mild disease, or died from an apparently unrelated cause. A new genetic change is possible but less common.

Genetic counseling can help individuals and families understand inheritance, testing options, privacy considerations, and the possible emotional impact of results. Testing is a personal decision and should be supported by clinicians experienced in hereditary conditions.

Diagnosis and Organ Assessment

Diagnosing hATTR amyloidosis requires a combination of clinical evaluation, family history, and testing. A doctor may suspect it when progressive neuropathy occurs with autonomic symptoms, cardiomyopathy, carpal tunnel syndrome, unexplained weight loss, or a family history of amyloidosis or similar symptoms.

A blood or saliva genetic test can identify a TTR gene variant. When a variant is found, specialists interpret it alongside symptoms and other findings, since not every genetic change has the same clinical significance. Genetic counseling is generally recommended before and after testing.

Tests may also be used to assess affected organs and exclude other forms of amyloidosis. These can include blood and urine tests for abnormal proteins, nerve conduction studies, autonomic testing, electrocardiography, echocardiography, cardiac magnetic resonance imaging, and certain nuclear medicine scans. In selected situations, a tissue biopsy may be needed to confirm amyloid deposits and determine their protein type.

A complete evaluation is important because treatment choices and follow-up depend on whether the nerves, heart, or other organs are involved. Regular assessments can also identify changes before they have a major effect on daily life.

Treatment Options and Supportive Care

Treatment aims to slow or reduce further amyloid formation, protect organ function, and relieve symptoms. The best approach depends on the person’s TTR variant, symptoms, disease stage, and whether nerve or heart involvement is present. Care is often coordinated among neurologists, cardiologists, genetic specialists, physiotherapists, gastroenterologists, and other professionals.

Disease-modifying medicines may work in two main ways: some reduce production of transthyretin by the liver, while others stabilize the transthyretin protein so it is less likely to separate and form deposits. The choice of therapy is individualized, and clinicians review potential benefits, monitoring needs, other health conditions, and local availability.

Supportive treatment remains essential. It may include medicines and practical measures for nerve pain, blood-pressure changes on standing, bowel symptoms, fluid retention, heart rhythm problems, nutrition, mobility, and sleep. Physiotherapy, occupational therapy, mobility aids, and dietary support may help preserve independence and quality of life.

Liver transplantation was historically used for selected people because the liver produces most transthyretin. It may still be considered in limited circumstances, but medication-based approaches have changed management for many patients. In advanced organ disease, specialist teams may discuss additional options, including transplant assessment where appropriate.

Living With hATTR Amyloidosis: Monitoring and Self-Care

There is no proven lifestyle measure that prevents a TTR gene variant from causing hATTR amyloidosis. However, regular follow-up and day-to-day measures can help manage symptoms and reduce avoidable complications. People should attend recommended neurological and cardiac reviews even when symptoms seem stable.

Maintaining adequate nutrition and hydration is particularly important if diarrhea, nausea, early fullness, or weight loss are present. A clinician or dietitian can offer individualized advice. Gentle, appropriate activity and physiotherapy may help with strength, balance, and cardiovascular conditioning, but exercise plans should be adapted if dizziness, weakness, or heart symptoms occur.

Standing up slowly, using supportive footwear, checking the feet for injuries when sensation is reduced, and discussing fall prevention can be helpful. Alcohol, dehydration, and medicines that lower blood pressure may worsen dizziness in some people, so medication changes should always be reviewed with a healthcare professional rather than made independently.

Relatives who may be at risk can consider genetic counseling. For people who test positive but do not have symptoms, specialists may recommend periodic monitoring rather than treatment, depending on the genetic variant and individual circumstances.

When to Seek Medical Care

A person should arrange a medical appointment if they have progressive tingling, burning pain, numbness, weakness, unexplained dizziness when standing, persistent digestive changes, or worsening fatigue—especially if there is a family history of hATTR amyloidosis, amyloidosis, unexplained neuropathy, or cardiomyopathy. These symptoms have many possible causes, and evaluation can help identify the right explanation.

Prompt medical review is important for new or worsening breathlessness, ankle swelling, fainting, chest discomfort, palpitations, or rapidly declining ability to walk or carry out everyday tasks. Sudden severe chest pain, severe shortness of breath, or loss of consciousness requires emergency assessment.

People with an identified TTR variant should seek specialist advice about a baseline evaluation and follow-up schedule, even if they feel well. Acıbadem Health Point’s multidisciplinary specialists and JCI-accredited hospitals provide diagnostic assessment and treatment planning for international patients with suspected or confirmed hATTR amyloidosis.

Frequently asked questions