Amyloidosis is officially classified as a rare disease, but “rare” depends on which type you’re talking about. The most commonly diagnosed form, AL amyloidosis, affects roughly 17 out of every million adults per year in the United States. Another major form, wild-type ATTR amyloidosis, may be far more common than those numbers suggest because it goes undetected in a large number of older adults with heart failure.
How Amyloidosis Is Classified as Rare
In the U.S., a disease qualifies as “rare” when fewer than 200,000 people have it at any given time. Every subtype of amyloidosis falls well below that threshold. AL amyloidosis, the type caused by abnormal antibody fragments, has a global incidence of roughly 1 in 96,000 people. Hereditary ATTR amyloidosis (caused by an inherited gene mutation) is even less common, estimated at about 1 in 450,000 globally. AA amyloidosis, triggered by chronic inflammatory conditions, sits at roughly 1 to 2 cases per million people per year and appears to be declining.
Despite these small numbers, the total count of people living with amyloidosis is growing. U.S. prevalence of AL amyloidosis nearly doubled between 2019 and 2021, rising from about 38 to 69 cases per million adults. That increase likely reflects better detection and longer survival rather than a true surge in new cases.
AL Amyloidosis: The Most Commonly Diagnosed Type
AL amyloidosis develops when certain white blood cells in the bone marrow produce misfolded protein fragments that accumulate in organs. It accounts for the majority of diagnosed amyloidosis cases. Annual incidence in the U.S. has been estimated between 10 and 17 cases per million adults, depending on the study period and data source. A 20-year look at global data identified roughly 73,500 cases total, with about 15,000 new diagnoses in 2018 alone.
The disease overwhelmingly affects older adults. Nearly 45% of new cases occur in people 65 and older, and another 33% in those between 55 and 64. The average age at diagnosis is 64. Men over 65 have the highest rates of any demographic group. Younger adults aren’t immune, but only about 1.4% of cases appear in people under 35.
ATTR Amyloidosis: Likely Underdiagnosed
Transthyretin amyloidosis comes in two forms. The hereditary version (ATTRv) is caused by a gene mutation passed through families. The wild-type version (ATTRwt) happens when the normal transthyretin protein, which the liver produces to carry thyroid hormone and vitamin A, becomes unstable with aging and deposits in the heart. On paper, ATTRwt looks extremely rare. In Tuscany, Italy, where tracking is unusually thorough, the incidence is about 1 in 37,500.
But those official numbers almost certainly undercount the true burden. Studies of older heart failure patients suggest that up to 15% of those with certain cardiovascular profiles actually have undiagnosed ATTR amyloidosis. That’s a staggering gap between how many people have the disease and how many know it. The condition hides in plain sight because its symptoms, especially progressive heart failure and thickening of the heart wall, overlap with much more common diagnoses.
Hereditary ATTR amyloidosis is rarer overall but concentrated in specific populations. About 3 to 4% of African Americans carry the V122I gene variant, which can cause a form of cardiac amyloidosis that typically surfaces in the seventh decade of life. Cardiac symptoms often appear a full decade before anyone connects them to amyloidosis. This means tens of thousands of carriers exist in the U.S. alone, though only a fraction develop symptomatic disease.
AA Amyloidosis: Declining Thanks to Better Treatments
AA amyloidosis is a complication of chronic inflammatory diseases like rheumatoid arthritis, ankylosing spondylitis, and juvenile idiopathic arthritis. The body produces a protein called serum amyloid A during prolonged inflammation, and over years, fragments of that protein can build up in organs, especially the kidneys.
This type has become significantly rarer in recent decades. Among people with rheumatoid arthritis, prevalence rates ranged from 17 to 25% in studies conducted before 2010. After 2010, that figure dropped to about 0.7%. A similar pattern appeared in ankylosing spondylitis, where rates fell from 6 to 8.5% down to roughly 1%. The most likely explanation is the widespread adoption of biologic therapies that effectively suppress the underlying inflammation before amyloid deposits have a chance to form.
Why So Many Cases Are Missed
Amyloidosis is not just rare in the statistical sense. It’s rare in the diagnostic sense, meaning many doctors go years or an entire career without seeing a case. That unfamiliarity contributes to significant delays. For AL amyloidosis involving the heart, the average time from first symptoms to a correct diagnosis is about 10.5 months, though some patients wait over four years. More than two-thirds of cardiac AL patients are ultimately referred to the right specialist by a cardiologist, meaning they’ve already navigated at least one other step in the system before landing on the correct diagnosis.
ATTR cardiac amyloidosis faces similar problems. An analysis of nearly 2,000 ATTR patient records found a misdiagnosis rate of 26%. The most common wrong diagnosis was hypertrophic cardiomyopathy (thickened heart muscle from a different cause), which accounted for 53% of misdiagnoses. Another 20% were initially told they had coronary artery disease. These misdiagnoses matter because treatments for those conditions do nothing to slow amyloid buildup, and some standard heart failure medications can actually worsen symptoms in amyloidosis patients.
Awareness is improving. The 2025 guidance from the American College of Cardiology highlights that ATTR amyloidosis should be considered in heart failure patients who also have bilateral carpal tunnel syndrome or spinal stenosis, two musculoskeletal problems that often show up years before the heart symptoms become obvious.
Survival Rates Have Improved Substantially
Historically, an AL amyloidosis diagnosis carried a grim prognosis. Data spanning four decades shows that outcomes have improved markedly. For patients diagnosed between 2010 and 2019, the median survival was 4.6 years, and the five-year survival rate reached 48%. Six-month mortality dropped to 13%, a significant improvement over earlier eras when many patients didn’t survive the first year. These gains are driven by newer treatment regimens that target the abnormal cells producing the harmful protein.
ATTR amyloidosis generally progresses more slowly than AL amyloidosis, particularly the wild-type form, which tends to affect people in their late 70s and 80s. Therapies that stabilize the transthyretin protein or reduce its production have changed the outlook for both hereditary and wild-type forms, though long-term survival data for these newer treatments is still accumulating.
Putting the Numbers in Perspective
If you compare amyloidosis to other conditions, the incidence of AL amyloidosis (about 17 per million) is roughly similar to chronic myeloid leukemia and about one-tenth as common as multiple myeloma, a related blood cancer that also involves abnormal plasma cells. Wild-type ATTR, if the higher estimates from heart failure screening studies prove accurate, could be orders of magnitude more common than current diagnosis rates suggest.
The practical takeaway is that amyloidosis is genuinely rare by formal criteria, but it’s also genuinely underdiagnosed. The gap between those two realities is where patients get lost in the system. If you or someone you know has unexplained heart failure with a thickened heart wall, progressive nerve damage in the hands and feet, or unexplained kidney problems alongside a chronic inflammatory condition, amyloidosis belongs on the list of possibilities even if it seems unlikely.