Prevalence Study Finds FAP May Be More Common Worldwide Than Previously Thought

An assessment of the global prevalence of familial amyloid polyneuropathy, caused by mutations in the transthyretin (TTR) gene, gave a similar count to that estimated in earlier studies. But the uppermost number in its range — that of 38,468 affected people — was notably higher.

That upper estimate, in the study funded by Pfizer and conducted by researchers at Muenster University Hospital in Germany,  led the scientists to argue that it is necessary to improve epidemiological and clinician awareness of this disease because it “implies potentially higher prevalence,” they wrote

The study, “Estimating the global prevalence of transthyretin familial amyloid polyneuropathy,” was published in the journal Muscle & Nerve.

Earlier estimates of TTR-FAP state that 5,000 to 10,000 people globally are affected by this type of the disease. But these estimates do not appear to have been formally or transparently made, the researchers said. Their work put the mid-global prevalence estimate at 10,186.

In their attempt at a new assessment, the researchers gathered data from published scientific studies between 2005 and 2016. In addition, they included data presented at conferences and information from non-peer-reviewed sources. The team then assessed the evidence strength of the material to include only the most reliable sources.

The final analysis included 10 studies. Two of them reported on prevalence in the U.S. and Brazil, respectively, while the remaining eight studies reported on prevalence in 11 countries. Among them, there were 10 estimates of national prevalence rates.

The researchers used these figures as a core group of countries with more solid data to make estimates about other regions. In their calculations, researchers took into account if a country was considered endemic or not. Portugal, Sweden and some areas in Japan are considered endemic, since the disease is more common there.

In the core group, an estimated 3,762 people were thought to be affected by FAP. Most were in Portugal, which had an estimate of 2,051 patients.

By extrapolating these findings, the team concluded that across 42 countries worldwide, an estimated 10,186 persons had FAP. Estimates ranged from 5,526 to 38,468.

Researchers said that the 42 countries made up only 60 percent of the world population. This indicates that many more, affected by FAP, may be found in the remaining 40 percent of the population, particularly in former Portuguese colonies such as Angola, Cape Verde, Equatorial Guinea, and Mozambique.

This work highlights the need to focus more resources on surveillance, epidemiological assessment, diagnostics, specialty care, and increased clinician knowledge in FAP and other rare diseases.

The researchers hope that their findings may encourage clinicians to consider FAP as a diagnosis when examining patients with unexplained polyneuropathy.