Epidemiology of transthyretin-associated familial amyloid polyneuropathy in the Majorcan area: Son Llatzer Hospital descriptive study

Background: Transthyretin-associated Familial Amyloid Polyneuropathy (TTR-FAP) is an autosomal dominant disease caused by the deposition of abnormal transthyretin that results from a gene mutation. Although rare worldwide, there are descriptions of several endemic foci, such as in Majorca, Balearic Islands, Spain. We aimed at describing a contemporary series of TTR-FAP patients in Son Llatzer Hospital in Majorca from an epidemiological point of view in order to report their main clinical and laboratory characteristics. Methods: A retrospective, observational study was performed. Medical records from adult patients diagnosed with TTR-FAP from a single hospital were reviewed. Results: Out of a total of 107 cases, 75 subjects were included: asymptomatic carriers (52.3%) and symptomatic patients (47.7%). Mean age was 58.3 years at the time of the study, and 50.7% were men. Mean age at diagnosis was 49.8 years. In addition, 42 patients (39.2%) had received a liver transplant, and time to liver transplantation was on average 29.56 months from the initial diagnosis. They all had the Val30Met mutation. The organs of the nervous system were those most frequently impaired (57.3%), and 83.9% of the symptomatic patients were fully ambulant (stage 1). Family history was reported in 69.3% of the cases, with the patient's father being the most commonly affected relative. Comorbidities were frequent, with high blood pressure being the most common. Conclusions: Our findings provide additional information on this condition and are useful for describing the demographic features, clinical presentation, diagnosis, and natural course of TTR-FAP in Majorca.