Aims: Familial amyloid polyneuropathy (FAP) is a dominantly inherited multi-system disease associated with transthyretin (TTR) mutations. Previous series have predominantly described patients with the TTR variant Val30Met (V30M), which is the most prevalent cause of FAP worldwide. Here, we report the dominant cardiac phenotype and outcome of FAP associated with TTR Thr60Ala (T60A), the most common UK variant.
Methods and results: Sixty consecutive patients with FAP associated with TTR T60A (FAP T60A) were prospectively evaluated in two centres between 1992 and 2009. Median (range) age of symptom development was 63 (45-78) years. A family history of amyloidosis was present in only 37%. Autonomic and peripheral neuropathy were present in 44 and 32 patients, respectively, at diagnosis. Cardiac involvement was evident on echocardiography at diagnosis in 56 patients, but was associated with reduced QRS voltages on electrocardiography in only 16% evaluable cases. Seventeen patients received implantable anti-arrhythmic devices. Median survival was 6.6 years following onset of symptoms and 3.4 years from diagnosis, and correlated with serum N-terminal prohormone brain natriuretic peptide (NT-proBNP) concentration and certain echocardiographic parameters at the latter. Orthotopic liver transplantation (OLT), performed to eliminate the predominant hepatic source of variant TTR T60A protein, was performed in eight patients including one who received a concomitant cardiac transplant. Cardiac amyloidosis progressed in all lone OLT recipients, of whom four died within 5 years.
Conclusion: Cardiac amyloidosis is almost always present at diagnosis in FAP T60A, and is a major determinant of its poor prognosis. Outcome of liver transplantation in FAP T60A has been discouraging.