Hereditary transthyretin amyloidosis (ATTRv, v for variant) is a severe and heterogeneous systemic condition due to mutations in the transthyretin (TTR) gene. The availability of disease-modifying therapies has led to an urgent need to have reliable biomarkers capable of assessing the clinical severity of the disease and of monitoring the efficacy of pharmacological treatment. At the same time, early markers for the clinical onset of ATTRv amyloidosis in presymptomatic subjects are needed to enable earlier initiation of anti-amyloid therapy. In this project the investigators seek to achieve three main goals: to identify and validate disease severity biomarkers in symptomatic patients; to establish disease onset biomarkers of ATTRv amyloidosis in presymptomatic subjects; to explore new pathogenetic mechanisms underlying this multisystem disorder, such as mitochondrial dysfunction and immune response.