Amyloidosis, Hereditary

The study design is a prospective registry including asymptomatic and symptomatic patients who carry a pathogenic TTR mutation. The study will enroll patients who meet the inclusion criteria and none of the exclusion criteria until 1000 patients are enrolled, at which point in time the study investigators will evaluate whether further patient accrual is meaningful.

Approximately 1.5 million of the 44 million Blacks in the United States are carriers of the valine-to-isoleucine substitution at position 122 (V122I) in the transthyretin (TTR) protein. Virtually exclusive to Blacks, this is the most common cause of hereditary cardiac amyloidosis (hATTR-CA) worldwide. hATTR-CA leads to worsening heart failure (HF) and premature death. Fortunately, new therapies that stabilize TTR improve morbidity and mortality in hATTR-CA, especially when prescribed early in the disease. However, hATTR-CA is often diagnosed at an advanced stage and conventional diagnostic tools lack diagnostic specificity to detect early disease. The overall objectives of this study are to determine the presence of subclinical hATTR-CA and to identify biomarkers that indicate amyloid progression in V122I TTR carriers. The central hypothesis of this proposal is that hATTR-CA has a long latency period that will be detected through subclinical amyloidosis imaging and biomarker phenotyping. The central hypothesis will be tested by pursuing 2 specific aims: Aim 1) determine the association of V122I TTR carrier status with CMRI evidence of amyloid infiltration; Sub-aim 1) determine the association of V122I TTR carrier status with cardiac reserve; Aim 2) determine the association between amyloid-specific biomarkers and V122I TTR carrier status; and Sub-aim 2) determine the association of amyloid-specific biomarkers with imaging-based parameters and evaluate their diagnostic utility for identifying subclinical hATTR-CA. In Aim 1, CMRI will be used to compare metrics associated with cardiac amyloid infiltration between a cohort of V122I TTR carriers without HF formed by cascade genetic testing and age-, sex-, and race-matched non-carrier controls. For Sub-Aim 1, a sub-sample of carriers and non-carrier controls enrolled in Aim 1 will undergo novel exercise CMRI to measure and compare cardiac systolic and diastolic reserve. Aim 2 involves measuring and comparing amyloid-specific biomarkers in V122I TTR carriers without HF with samples matched non-carriers (both from Aim 1) and individuals with symptomatic V122I hATTR-CA from our clinical sites. These biomarkers detect and quantify different processes of TTR amyloidogenesis and include circulating TTR, retinol binding protein 4, TTR kinetic stability, and misfolded TTR oligomers. Sub-aim 2 will establish the role of these biomarkers to detect imaging evidence of subclinical hATTR-CA disease.

This study will be conducted to evaluate the efficacy and safety of a single dose of nexiguran ziclumeran (NTLA-2001) compared to placebo in participants with ATTRv-PN.

This study explores whether extracellular vesicles (EVs) tiny particles released into the bloodstream by cells can serve as early and minimally invasive biomarkers for transthyretin amyloid cardiomyopathy (ATTR-CM). Because ATTR-CM is often diagnosed only after significant heart damage has occurred, there is an urgent need for earlier detection methods. The study will enroll individuals with different clinical presentations of transthyretin amyloidosis, along with healthy controls. Participants will undergo blood sampling, cardiac imaging (including echocardiography, cardiac MRI, and scintigraphy when indicated), and molecular EV analysis. By comparing EV profiles across groups, the study aims to determine whether these vesicles reflect early cardiac involvement, track disease progression, and support more accurate and timely diagnosis. Ultimately, this research seeks to improve clinical decision-making and patient outcomes in ATTR cardiomyopathy.