Hereditary transthyretin amyloidosis (hATTR) is a rare, progressive disease caused by an inherited gene mutation that makes a liver protein misfold and deposit in organs throughout the body, gradually damaging the nerves, heart, and digestive system. An estimated 10,000 to 40,000 people worldwide have the hereditary form, though the true number is likely higher because the disease is frequently misdiagnosed or caught late. Amyloid deposits can begin building up years before any symptoms appear, similar to the silent early stages of Alzheimer’s or Parkinson’s disease.
How the Disease Works
Your liver produces a protein called transthyretin (TTR), which normally circulates in the blood as a stable, four-part structure called a tetramer. Its job is to carry thyroid hormone and vitamin A. In hATTR, a mutation in the TTR gene makes that four-part structure unstable. The tetramer breaks apart into single units, which then misfold and clump together into stiff, insoluble fibers called amyloid fibrils. These fibrils accumulate outside cells in tissues throughout the body, physically disrupting organ function over time.
Where the amyloid deposits land determines which symptoms appear first. In some people, fibrils concentrate around peripheral nerves. In others, they infiltrate the heart muscle. Many patients eventually develop problems in both systems, plus the gastrointestinal tract and other organs.
The Genetic Mutations Behind hATTR
More than 130 TTR mutations have been identified, but three account for the vast majority of cases in the United States. The most common by far is the V142I variant, found in about 84% of patients referred for genetic testing. This mutation primarily causes heart-related disease and disproportionately affects Black individuals, with carrier rates estimated at 3 to 4% in African Americans. The T80A variant (about 5% of cases) also tends to affect the heart, while the V50M variant (about 4%) is more closely linked to nerve damage and is historically concentrated in endemic regions like Portugal, Japan, Sweden, and Brazil.
Because the disease is inherited in an autosomal dominant pattern, you only need one copy of the mutated gene to develop it. That also means each child of an affected parent has a 50% chance of inheriting the mutation, though not everyone who carries it will develop symptoms at the same age or severity.
Early Warning Signs
The earliest symptoms of hATTR are easy to mistake for common, unrelated problems, which is a major reason the average time to diagnosis stretches years beyond symptom onset. Autonomic nerves are often the first to be affected, sometimes before any obvious numbness or weakness. Early autonomic symptoms include dizziness or lightheadedness when standing up, erectile dysfunction, and alternating bouts of diarrhea and constipation.
Small fiber neuropathy also appears early, causing pain, tingling, or numbness that typically starts in the feet and works its way upward. Many patients are initially treated for conditions that turn out to be amyloid-related: carpal tunnel syndrome (sometimes in both hands), lumbar spinal stenosis, ruptured biceps tendons, or trigger finger. A history of multiple orthopedic procedures in midlife, especially combined with nerve symptoms or unexplained heart problems, is a red flag that clinicians are increasingly taught to recognize.
Nerve and Autonomic Symptoms
As the disease progresses, sensory neuropathy extends from the feet into the legs and eventually the hands. Muscle weakness follows, leading to gait imbalance, difficulty walking, and falls. Autonomic dysfunction worsens in parallel, often producing severe orthostatic hypotension (blood pressure drops dramatically when you stand, causing fainting or blurred vision), chronic nausea, vomiting, early fullness after eating, and significant unintentional weight loss. These autonomic features can be an important diagnostic clue: most other causes of adult-onset progressive neuropathy do not produce this degree of autonomic involvement.
Cardiac Involvement
When amyloid fibrils infiltrate the heart, they stiffen the muscle wall and interfere with its ability to relax and fill properly. This leads to heart failure with preserved ejection fraction, meaning the heart still squeezes normally but cannot fill with enough blood between beats. Patients develop shortness of breath, exercise intolerance, and fluid retention. Atrial fibrillation is common, and some patients eventually need a pacemaker due to slowed electrical conduction through amyloid-infiltrated tissue.
Left untreated, heart failure from ATTR cardiomyopathy carries a life expectancy of only 2.5 to 3.5 years. But when the disease is caught before heart failure symptoms develop, five-year survival reaches about 82%, and treatment with protein-stabilizing medications significantly improves those numbers. In one study, treated patients had an 82% lower risk of death after adjusting for age, sex, and disease type.
How hATTR Is Diagnosed
Diagnosis follows a stepwise process. The first priority is ruling out a different type of amyloidosis called AL amyloidosis, which is caused by abnormal immune cells rather than a TTR mutation and requires completely different treatment. Blood and urine tests can screen for the abnormal proteins that cause AL amyloidosis.
Once AL is excluded, a nuclear bone scan (using a radioactive tracer that binds to TTR amyloid deposits) can confirm amyloid in the heart without a biopsy. This scan has become a game-changer in diagnosis, sparing many patients from invasive tissue sampling. Genetic testing then determines whether the ATTR is hereditary or wild-type. If a known pathogenic TTR mutation is found, the diagnosis is hATTR. If the genetic test is normal but the bone scan is positive, the diagnosis is wild-type ATTR, an age-related form unrelated to inherited mutations.
For patients whose primary symptoms are neurological, diagnosis also involves nerve conduction studies and clinical assessments of sensory loss, motor weakness, reflex changes, and autonomic function.
Treatment: Stabilizers and Silencers
Two fundamentally different treatment strategies exist for hATTR, and they target different steps in the disease process.
TTR stabilizers work by binding to the intact four-part TTR protein and holding it together, preventing it from breaking apart into the misfolded fragments that form amyloid. Tafamidis and acoramidis are both oral stabilizers approved for ATTR cardiomyopathy. In a landmark 30-month trial, tafamidis reduced all-cause mortality by 30% compared to placebo (29.5% vs. 42.9%) and lowered cardiovascular hospitalizations by 32%. Both medications are taken daily by mouth.
TTR gene silencers take a more aggressive approach: they reduce the liver’s production of TTR protein altogether, cutting off the supply of raw material that can misfold. Patisiran, vutrisiran, and eplontersen are all approved for the polyneuropathy form of hATTR. Vutrisiran is particularly convenient, given as a small injection under the skin once every three months. Indirect comparisons suggest gene silencers are more effective than stabilizers at slowing nerve damage, likely because the misfolded protein fragments in hereditary disease are directly toxic to nerves in a way that goes beyond simple physical infiltration.
For cardiac disease specifically, tafamidis and acoramidis remain the approved options, though vutrisiran and eplontersen are being studied in large trials for this indication. Inotersen, an earlier gene silencer, has been withdrawn from the U.S. market due to its less favorable safety profile compared to newer alternatives.
Living With hATTR
Because hATTR is a multisystem disease, management typically involves a team that includes a cardiologist, neurologist, and gastroenterologist. Symptom management matters alongside disease-modifying therapy. Orthostatic hypotension may require compression stockings, increased salt intake, and careful adjustment of any blood pressure medications (which patients with amyloid cardiomyopathy often cannot tolerate). Neuropathic pain is managed with medications that calm overactive nerve signals. Nutritional support is important for patients with gastrointestinal involvement and weight loss.
Genetic testing of family members is recommended once a pathogenic mutation is identified in a patient. Relatives who carry the mutation can be monitored for early signs of the disease, and starting treatment before significant organ damage accumulates leads to substantially better outcomes. About 32% of patients diagnosed with early-stage cardiac involvement progressed to heart failure symptoms within five years in one study, reinforcing the value of catching the disease before it advances.