Hereditary ATTR amyloidosis is rare, but a reliable UK prevalence estimate needs a defined population, date and case definition. The sources examined for this article do not establish one current total for everyone living with symptomatic hereditary ATTR across the UK. Numbers for all ATTR cardiomyopathy, genetically identified carriers or a specialist clinic should not be substituted for that total.
This is why two apparently different answers to “How many people have hATTR in the UK?” may not actually contradict one another. They may be counting different people.
First decide what is being counted
| Measure | Who or what it counts | Common misinterpretation |
|---|---|---|
| Variant-carrier frequency | People or alleles carrying a specified TTR variant | Treating every carrier as having symptomatic disease |
| Disease prevalence | People living with a defined condition at a specified time | Using an undated cumulative clinic total |
| Incidence | New cases arising over a defined period | Presenting annual new cases as all current cases |
| Specialist cohort proportion | A subgroup among patients assessed by a service or study | Applying that percentage to the general population |
“ATTR” includes hereditary disease and wild-type disease unless the source explicitly separates them. “ATTR-CM” identifies a cardiomyopathy phenotype; it does not automatically include all people with hereditary ATTR presenting through neuropathy. Our main ATTR guide explains these clinical categories.
What a large UK study actually showed
A study published in 2023 examined 2,029 patients aged at least 70 years with ATTR cardiomyopathy assessed at the UK National Amyloidosis Centre between January 2010 and August 2022. It identified pathogenic TTR variants in 421 patients, or 20.7% of that cohort. Read the original study and its methods.
The denominator was older patients with diagnosed ATTR cardiomyopathy who met the study criteria. It was not the UK population. The figure therefore helps answer a clinical question about hereditary disease within that selected group; it does not mean that 20.7% of older UK residents have hereditary ATTR.
Why a clinic count is not a national headcount
A referral centre may see people diagnosed over many years, people from outside the intended population and people assessed without ultimately meeting the same diagnostic definition. A registry may contain both living and deceased participants. Some affected people may never reach the centre. None of these possibilities makes the registry unhelpful; they determine which questions its data can answer.
The National Amyloidosis Centre is a major specialist source for UK diagnostic and clinical information. Its patient population and service role should be described accurately whenever its numbers are quoted.
Why carrier frequency cannot supply the missing number
The analysis of TTR variants in large sequencing datasets estimates allele frequencies in the populations represented in those datasets. Such estimates can inform research on genetic susceptibility. They do not directly count symptomatic UK cases.
Multiplying an allele frequency by the UK population would require assumptions about ancestry representation, carrier frequency, penetrance, age structure and case definition. Leaving those assumptions unstated can produce a precise-looking number with an unclear meaning. A population from a founder region also should not be treated as representative of the whole UK.
A practical way to evaluate a prevalence claim
- Record the original source and publication date.
- Identify the geography: UK, a constituent nation, a region or a referral service.
- Check whether the count includes ATTRwt as well as ATTRv.
- Check whether carriers without clinical disease are included.
- Find the denominator and the date or observation period.
- Read how cases were identified and what might have been missed.
- Quote the estimate with its definition and uncertainty, rather than extracting the number alone.
Fictional teaching example. A report says that a service treated 500 people with “ATTR cardiomyopathy.” Before using that figure in a patient leaflet about hereditary ATTR, an editor asks whether it includes wild-type disease, which year it covers and whether it represents unique living patients. Those answers determine whether the number belongs in the leaflet at all. The number 500 is illustrative, not a UK estimate.
What should patients and families take from this uncertainty?
National frequency does not decide an individual diagnosis. Symptoms, organ investigations and a properly interpreted TTR result are more relevant to personal assessment. A rare condition can still be the correct diagnosis in a well-investigated individual, while a family association does not make every nonspecific symptom attributable to it.
For clinical background, use the NHS hereditary systemic amyloidosis guide. For variant-specific questions, read T60A and p.Thr80Ala explained. Our research comparison tools can help record the population, numerator and denominator when reviewing a new epidemiological paper.