Sixty years of transthyretin familial amyloid polyneuropathy (TTR-FAP) in Europe: where are we now? A European network approach to defining the epidemiology and management patterns for TTR-FAP

Cardiovascular Involvement in Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is a systemic disorder resulting from the extracellular deposition of amyloid fibrils of misfolded transthyretin protein in the heart. ATTR-CA is a life-threatening disease, which can be caused by progressive deposition of wild type transthyretin (wtATTR) or by aggregation of an inherited mutated variant of transthyretin (mATTR). mATTR Is a rare condition transmitted in an autosomal dominant manner with incomplete penetrance, causing heterogenous phenotypes which can range from predominant neuropathic involvement, predominant cardiomyopathy, or mixed. Diagnosis of ATTR-CA is complex and requires integration of different imaging tools (echocardiography, bone scintigraphy, magnetic resonance) with genetics, clinical signs, laboratory tests, and histology. In recent years, new therapeutic agents have shown good efficacy and impact on survival and quality of life in this subset of patients, nevertheless patients affected by ATTR-CA may still carry an unfavorable prognosis, thus highlighting the need for new therapies. This review aims to assess cardiovascular involvement, diagnosis, and management of patients affected by ATTR-CA.

Characterization of hereditary transthyretin cardiac amyloidosis in Spain

INTRODUCTION AND OBJECTIVES

Hereditary transthyretin amyloidosis (hATTR) is a disease caused by mutations in the transthyretin gene that frequently shows cardiac involvement due to amyloid deposition in the myocardium. Our objective was to identify cardiac involvement in a Spanish cohort.

METHODS

Retrospective multicenter study of patients diagnosed with hATTR with cardiac involvement from Spanish centers. We collected demographic, clinical, and genetic data.

RESULTS

A total of 181 patients from 26 centers were included (65.2% men, with a median age at diagnosis of 62 years). The most frequent mutations were Val50Met (67.7%) and Val142Ile (12.4%). The main reason for consultation was extracardiac symptoms (69%), mainly neurological. The mean N-terminal pro-B-type natriuretic peptide level was 2145±3586 pg/mL. The most characteristic electrocardiogram findings were a pseudoinfarct pattern (25.9%) and atrioventricular block (25.3%). Mean ventricular thickness was 15.4±4.1mm. Longitudinal strain was reduced in basal segments by 29.4%. Late diffuse subendocardial enhancement was observed in 58.8%. Perugini grade 2 or 3 uptake was observed in 75% of scintigraphy scans. During follow-up, 24.9% of the patients were admitted for heart failure, 34.3% required a pacemaker, and 31.6% required a liver transplant. One third (32.5%) died during follow-up, mainly due to heart failure (28.8%). The presence of non-Val50Met mutations was associated with a worse prognosis.

CONCLUSIONS

HATTR cardiac amyloidosis in Spain shows heterogeneous genetic and clinical involvement. The prognosis is poor, mainly due to cardiac complications. Consequently early diagnosis and treatment are vital.

Epidemiology of variant transthyretin amyloidosis at a reference center in Argentina

Background

In Argentina, there is limited data of prevalence of variant transthyretin amyloidosis (ATTRv) and phenotype‐genotype correlation. The laboratory of Hospital Italiano de Buenos Aires (HIBA) is a reference center for transthyretin (TTR) gene sequencing. The Institutional Amyloidosis Registry (RIA) enable us to characterize people with ATTRv. Our aim was to describe the prevalence of TTR mutations at a reference center in Argentina and the phenotypic presentations of patients with ATTRv included in an institutional registry.

Methods

Retrospective cohort study of consecutive patients with genetic variants in the TTR gene identified from 2012 to 2019 in the laboratory. We collected all phenotypic characteristics of patients who were clinically evaluated by HIBA doctors.

Results

Five hundred seventy‐six patients tested, 141 positive: p.Val50Met 107, p.Thr80Ala 16, p.Ala117Ser 9, p.Phe84Leu 2, p.Ile127Val 2, p.Tyr134Cys 2, p.Ala56Pro 2, p.Val142Ile 1. Only 20 patients were clinically evaluated. The mean age at diagnosis was 54 years; 70% had family history with a pedigree median of 4. Mutations were p.Thr80Ala 9, p.Val50Met 6, p.Ala56Pro 2, p.Val142Ile 1, p.Phe84Leu 1, and p.Tyr134Cys 1. Eleven patients presented polyneuropathy, 11 had gastrointestinal compromise, six patients had autonomic compromise, six presented cardiac symptoms and four patients presented ocular involvement.

Conclusion

We present the first prevalence report of TTR mutations in a reference center of amyloidosis in Argentina. The most frequent genetic variant was p.Val50Met. Our data show considerable phenotypic heterogeneity in the patients with ATTRv.

Expert opinion on monitoring symptomatic hereditary transthyretin-mediated amyloidosis and assessment of disease progression

BACKGROUND

Hereditary transthyretin-mediated amyloidosis, also known as ATTRv amyloidosis (v for variant), is a rare, autosomal dominant, fatal disease, in which systemic amyloid progressively impairs multiple organs, leading to disability and death. The recent approval of disease-modifying therapies offers the hope of stabilization or eventual reversal of disease progression, and yet highlights a lack of disease-management guidance. A multidisciplinary panel of expert clinicians from France and the US came to consensus on monitoring the disease and identifying progression through a clinical opinion questionnaire, a roundtable meeting, and multiple rounds of feedback.

MONITORING DISEASE AND PROGRESSION

A multidisciplinary team should monitor ATTRv amyloidosis disease course by assessing potential target organs at baseline and during follow-up for signs and symptoms of somatic and autonomic neuropathy, cardiac dysfunction and restrictive cardiomyopathy, and other manifestations. Variability in penetrance, symptoms, and course of ATTRv amyloidosis requires that all patients, regardless of variant status, undergo regular and standardized assessment in all these categories. Progression in ATTRv amyloidosis may be indicated by: worsening of several existing quantifiable symptoms or signs; the appearance of a new symptom; or the worsening of a single symptom that results in a meaningful functional impairment.

CONCLUSIONS

We suggest that a multisystem approach to monitoring the signs and symptoms of ATTRv amyloidosis best captures the course of the disease. We hope this work will help form the basis of further, consensus-based guidance for the treatment of ATTRv amyloidosis.

Chance or challenge, spoilt for choice? New recommendations on diagnostic and therapeutic considerations in hereditary transthyretin amyloidosis with polyneuropathy: the German/Austrian position and review of the literature

Hereditary transthyretin amyloidosis is caused by pathogenic variants (ATTRv) in the TTR gene. Alongside cardiac dysfunction, the disease typically manifests with a severely progressive sensorimotor and autonomic polyneuropathy. Three different drugs, tafamidis, patisiran, and inotersen, are approved in several countries, including the European Union and the United States of America. By stabilizing the TTR protein or degrading its mRNA, all types of treatment aim at preventing amyloid deposition and stopping the otherwise fatal course. Therefore, it is of utmost importance to recognize both onset and progression of neuropathy as early as possible. To establish recommendations for diagnostic and therapeutic procedures in the follow-up of both pre-symptomatic mutation carriers and patients with manifest ATTRv amyloidosis with polyneuropathy, German and Austrian experts elaborated a harmonized position. This paper is further based on a systematic review of the literature. Potential challenges in the early recognition of disease onset and progression are the clinical heterogeneity and the subjectivity of sensory and autonomic symptoms. Progression cannot be defined by a single test or score alone but has to be evaluated considering various disease aspects and their dynamics over time. The first-line therapy should be chosen based on individual symptom constellations and contra-indications. If symptoms worsen, this should promptly implicate to consider optimizing treatment. Due to the rareness and variability of ATTRv amyloidosis, the clinical course is most importantly directive in doubtful cases. Therefore, a systematic follow-up at an experienced center is crucial to identify progression and reassure patients and carriers.

A descriptive study of transthyretin amyloidosis in a tertiary hospital without a referral unit

BACKGROUND AND OBJECTIVE

Transthyretin amyloidosis (ATTR) is a rare disease that is part of systemic amyloidosis and is life-threatening. It can affect all organs and systems, the most frequent being neurological and cardiac involvement. This study aims to detect possible ATTR cases and carry out a descriptive study of them.

MATERIAL AND METHODS

Descriptive single-centre study carried out in a tertiary hospital, which included patients with suspected ATTR between September 2016 and January 2020.

RESULTS

A total of 190 suspected ATTR patients were detected. The study includes 100 of these patients, as well as 10 relatives of patients in whom ATTR was detected in its genetic variant (ATTRv). In total, ATTRv was detected in 7 individuals (3 with a presymptomatic mutation of the disease), 16 patients with age-related ATTR and 31 individuals with unknown cardiac amyloidosis with the tests performed, which confirms the presence of this disease in non-endemic areas.

CONCLUSIONS

ATTR is a disease that must be taken into account in the differential diagnosis of patients with heart failure with preserved LVEF, especially if associated with neurological symptoms.

The genetics of cardiac amyloidosis

Heritable cardiac amyloidosis (CA) is an underrecognized cause of morbidity and mortality in the USA. It results from the accumulation of the misfolded protein transthyretin within the myocardium, resulting in amyloid transthyretin-associated cardiomyopathy (ATTR-CM). Over 150 different pathologic point mutations within the transthyretin gene have been identified, each carrying variable clinical phenotypes and penetrance. In the USA, the most common cause of hereditary ATTR is the Val122Ile point mutation, with a prevalence of 3.4-4.0% in North Americans of African and Caribbean descent. Among Caucasians with hereditary ATTR-CM, the V30M mutation is the most commonly identified variant. Overall, the incidence of ATTR disease in the USA has been increasing, likely due to an increase in practitioner awareness, utilization of new non-invasive imaging technologies for ATTR diagnosis, and the growth of multidisciplinary amyloid programs across the country. Yet significant numbers of patients with evidence of left ventricular thickening on cardiac imaging, senile aortic stenosis, and/or symptoms of heart failure with preserved ejection fraction likely have undiagnosed CA, especially within the African American population. With the emergence of new disease-modifying therapies for ATTR, recognition and the prompt diagnosis of CA is important for patients and their potentially affected progeny. Herein, we review the genetics of heritable CA as well as the importance of genetic counseling and testing for patients and their families.

Current Review of Leptomeningeal Amyloidosis Associated With Transthyretin Mutations

INTRODUCTION

Leptomeningeal amyloidosis (LA) represents a rare subtype of familial transthyretin (TTR) amyloidosis, characterized by deposition of amyloid in cranial and spinal leptomeninges. Of >120 TTR mutations identified, few have been associated with LA.

CASE REPORT

A 27-year-old male presented with a 2-year history of progressive symptoms including cognitive decline and right-sided weakness and numbness. Cerebrospinal fluid (CSF) analyses demonstrated high protein level. Gadolinium-enhanced magnetic resonance imaging (MRI) revealed extensive leptomeningeal enhancement over the surface of the brain and spinal cord. Pathologic analyses revealed a TTR mutation c.113A>G (p.D38G).

REVIEW SUMMARY

Fifteen mutations and genotype-phenotype correlation of 72 LA patients have been summarized to provide an overview of LA associated with transthyretin mutations. The mean age of clinical onset was 44.9 years and the neurological symptoms primarily included cognitive impairment, headache, ataxia seizures and hearing, visual loss. CSF analysis showed elevated high CSF protein level and MRI revealed extensive leptomeningeal enhancement.

CONCLUSION

Clinicians should be aware of this rare form of familial transthyretin amyloidosis as well as its typical MRI enhancement and high CSF protein. The important role of biopsy, genetic testing and the potential early diagnosis value of contrast MRI were suggested. Early recognition of these characteristics is important to provide misdiagnosis and shorten the time before correct diagnosis. These findings expand the phenotypic spectrum of TTR gene and have implications for the diagnosis, treatment, and systematic study of LA.

Variable Presentation of Hereditary Transthyretin-Mediated Amyloidosis at a Single Center

OBJECTIVES

Describe atypical presentations of hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy.

METHODS

Initial symptoms, diagnoses, and follow-up were recorded at the Austin Neuromuscular Center for 12 patients with nonclassical presentation of hATTR amyloidosis.

RESULTS

Common initial symptoms were hand and/or feet sensory manifestations (83%), muscle weakness (58%), and, less frequently, gastrointestinal and orthostatic impairment and carpal tunnel syndrome. Initial diagnoses were polyneuropathy (83%) and/or myopathy (25%). During follow-up, 10 patients (83%) developed cardiac symptoms (dyspnea, 67% and ankle edema, 17%), resulting in revised diagnoses of heart disease. Multisystem involvement raised suspicion of amyloidosis, which was confirmed by biopsy or nuclear scintigraphy, and genetic testing. All patients had polyneuropathy; 8 (67%) had cardiomyopathy-associated transthyretin mutations (V122I or T60A). Time from symptom onset to diagnosis was up to 10 years (median 5 years), during which patients' health deteriorated, although with recognition of disease signs/symptoms the diagnosis of hATTR amyloidosis was made in approximately 2-6 months from presentation at our center.

CONCLUSIONS

Increased awareness of the diverse initial hATTR amyloidosis symptoms could shorten time to diagnosis, enabling earlier treatment and improved patient outcomes.

Established and candidate transthyretin amyloidosis variants identified in the Saudi population by data mining

BACKGROUND

Familial transthyretin (TTR) amyloidosis (ATTR) is an autosomal dominant disease with significant phenotypic heterogeneity. Its prevalence in Saudi Arabia has not previously been investigated. An existing exome variant database of Saudi individuals, sequenced to globally investigate rare diseases in the population, was mined for TTR variants and filtered for missense mutations resulting in single amino acid changes. A total of 13,906 Saudi exomes from unrelated individuals were analyzed blindly.

RESULTS

Three TTR variants known to be associated with ATTR amyloidosis were identified. Additionally, three novel TTR mutations were identified. Structural analysis of the three novel variants suggests that at least two could be amyloidogenic. The most common variant associated with amyloidosis was p.Val142Ile (allele frequency 0.001). Further investigation of these variants and their translation to clinical practice may help to diagnose, monitor, and manage patients with ATTR amyloidosis.

CONCLUSION

Multiple TTR variants potentially associated with systemic ATTR amyloidosis were identified in the Saudi population. Early diagnosis and intervention, facilitated by familial genetic testing of patients with ATTR amyloidosis, may benefit in the management of this disease. Early diagnosis could be enhanced through inclusion of ATTR variants in existing population-based screening programs.

A Descriptive Analysis of ATTR Amyloidosis in Spain from the Transthyretin Amyloidosis Outcomes Survey

Introduction

Transthyretin amyloidosis (ATTR amyloidosis) is a clinically heterogeneous disease caused by mutations in the transthyretin (TTR) gene or aggregation of wild-type transthyretin (ATTRwt). In Spain, there are two large endemic foci of ATTR amyloidosis caused by the Val30Met variant, with additional cases across the country; however, these data may be incomplete, as there is no centralized patient registry. The Transthyretin Amyloidosis Outcomes Survey (THAOS) is an ongoing, global, longitudinal, observational survey of patients with ATTR amyloidosis, including both inherited and wild-type disease, and asymptomatic patients with TTR mutations. This analysis aimed to gain a deeper understanding of the clinical profile of patients with ATTR amyloidosis in Spain.

Methods

This was a descriptive analysis of the demographic and clinical characteristics of symptomatic patients enrolled at six sites geographically dispersed throughout Spain (data cutoff: January 6, 2020). Patient data at enrollment, including genotype, demographics, and clinical presentation for symptomatic patients, were recorded. Patients were grouped by predominant phenotype based on clinical measures at enrollment: predominantly cardiac, predominantly neurologic, or mixed (cardiac and neurologic).

Results

There were 379 patients (58.0% male; 63.3% symptomatic) enrolled in the six THAOS sites in Spain. Predominant genotypes were the Val30Met mutation (69.1%) or ATTRwt (15.6%). Predominant phenotype distribution was neurologic (50.4%), mixed (35.8%), and cardiac (13.8%) for all symptomatic patients (n = 240); neurologic (67.8%), mixed (21.2%), and cardiac (11.0%) for symptomatic Val30Met (n = 146); and mixed (64.9%), cardiac (22.8%), and neurologic (12.3%) for symptomatic ATTRwt (n = 57). Symptomatic patients reported a range of ATTR amyloidosis signs and symptoms at enrollment, with autonomic neuropathy and sensory neuropathy common in all phenotypes.

Conclusions

These results from THAOS highlight the phenotypic heterogeneity associated with ATTR amyloidosis in Spain and the importance of comprehensive neurologic and cardiac evaluations in all patients with ATTR amyloidosis.

Trial registration

ClinicalTrials.gov: NCT00628745.

Hereditary Transthyretin Amyloidosis- Clinical and Genetic Characteristics of a Multiracial South-East Asian Cohort in Singapore

BACKGROUND AND AIMS

Studies of hereditary transthyretin amyloidosis (ATTRv amyloidosis) in South-East Asia are underrepresented in the literature. We report the unique phenotypic and genetic characteristics of this disorder in a multiracial South-East Asian cohort.

METHODS

Patients with genetically proven ATTRv amyloidosis were identified over a 13-year period (2007-2020) at the National Neuroscience Institute, Singapore. Clinical, laboratory, genotypic and electrophysiological features were retrospectively reviewed.

RESULTS

29 patients comprising Chinese, Malay, Burmese, Vietnamese and Indonesians with ATTRv amyloidosis were identified. Somatic neuropathy was the most common initial presentation, followed by carpal tunnel syndrome, autonomic dysfunction and cardiac dysfunction. ATTR-A97S (p.Ala117Ser) was the most common variant found in 14 patients, constituting 66.7%of ethnic Chinese patients and 48.3%of the entire cohort. Five patients had early-onset disease (age < 50 years) with the following variants: ATTR-V30M (p.Val50Met), ATTR-G47A (p.Gly67Ala), ATTR-S50I (p.Ser70Ile) and ATTR-A97S (p.Ala117Ser); one patient with ATTR-A97S (p.Ala117Ser) had isolated unilateral carpal tunnel syndrome with amyloid deposits identified on histological examination of the transverse carpal ligament. All early-onset patients had a positive parental history; two patients, with ATTR-S50I (p.Ser70Ile) and ATTR-Ala97Ser (p.Ala117Ser) respectively, demonstrated anticipation with mother-to-daughter inheritance. Amongst the 24 patients with late-onset disease (age≥50 years), two patients had novel variants, ATTR-G66D (p.Glu86Asp) and ATTR-A81V (p.Ala101Val) that were confirmed to be pathogenic based on the histological identification of transthyretin amyloid. Other identified variants included ATTR-V30M (p.Val50Met), ATTR-R34T (p.Arg54Thr), ATTR-S50I (p.Ser70Ile), ATTR-H88R (p.His108Arg) and ATTR-A97S (p.Ala117Ser).

CONCLUSION

Our study further expands the genotypic and phenotypic knowledge regarding ATTRv amyloidosis.

Variant Transthyretin Amyloidosis (ATTRv) in Hungary: First Data on Epidemiology and Clinical Features

Background: Variant transthyretin amyloidosis (ATTRv) is an autosomal dominant inherited disease, where the mutation of the transthyretin gene (TTR) results in the deposition of pathogenic protein fibrils in various tissues. The mutation type influences the clinical course. Until now, no data were available on the genotype, phenotype, and prevalence of Hungarian ATTRv patients. The aim of our study was to assess the prevalence, regional distribution, genotypes, and phenotypes of Hungarian patients with ATTRv. Methods: With the collaboration of Hungarian regional and university centers, we identified patients diagnosed with ATTRv. We also searched prior publications for case studies of Hungarian ATTRv patients. Results: 40 individuals in 23 families with ATTRv were identified within the borders of Hungary. At the time of the diagnosis, 24 of them were symptomatic. The two most common mutations were ATTRHis88Arg (nine families) and ATTRIle107Val (8 families). ATTRVal30Met was demonstrated in 2 families, and ATTRVal122del, ATTRPhe33Leu, ATTRIle84Ser, and ATTRAsp18Gly in one family each. The median age of the symptomatic patients at the time of clinical diagnosis was 65 years. The most common clinically significant organ involvement was restrictive cardiomyopathy, found in 24 patients. Polyneuropathy was diagnosed in 20 patients. A total of 19 patients showed a mixed phenotype. The leading symptom was heart failure in 8 cases (3 of them had only cardiac symptoms), polyneuropathy in 11 cases (all of them also had cardiac symptoms), and equally severe cardiac and neuropathy symptoms were present in 3 cases. Out of 24 symptomatic patients, 10 received targeted pharmacological therapy. The follow-up period ranged from 1 to 195 months. At the time of the retrospective analysis, 12 patients had already died, and 1 patient underwent heart transplantation. Conclusions: As TTR genotype influences the phenotype and clinical course of ATTRv, it is important to know the regional data. In Hungary, ATTRHis88Arg and ATTRIle107Val are the most common mutations in ATTRv, both presenting with mixed phenotype, but the median age at the time of the diagnosis is 9 years lower in patients with ATTRHis88Arg than in patients with ATTRIle107Val.

Supporting the Assessment of Hereditary Transthyretin Amyloidosis Patients Based On 3-D Gait Analysis and Machine Learning

Hereditary Transthyretin Amyloidosis (vATTR-V30M) is a rare and highly incapacitating sensorimotor neuropathy caused by an inherited mutation (Val30Met), which typically affects gait, among other symptoms. In this context, we investigated the possibility of using machine learning (ML) techniques to build a model(s) that can be used to support the detection of the Val30Met mutation (possibility of developing the disease), as well as symptom onset detection for the disease, given the gait characteristics of a person. These characteristics correspond to 24 gait parameters computed from 3-D body data, provided by a Kinect v2 camera, acquired from a person while walking towards the camera. To build the model(s), different ML algorithms were explored: k-nearest neighbors, decision tree, random forest, support vector machines (SVM), and multilayer perceptron. For a dataset corresponding to 66 subjects (25 healthy controls, 14 asymptomatic mutation carriers, and 27 patients) and several gait cycles per subject, we were able to obtain a model that distinguishes between controls and vATTR-V30M mutation carriers (with or without symptoms) with a mean accuracy of 92% (SVM). We also obtained a model that distinguishes between asymptomatic and symptomatic carriers with a mean accuracy of 98% (SVM). These results are very relevant, since this is the first study that proposes a ML approach to support vATTR-V30M patient assessment based on gait, being a promising foundation for the development of a computer-aided diagnosis tool to help clinicians in the identification and follow-up of this disease. Furthermore, the proposed method may also be used for other neuropathies.

Val50Met hereditary transthyretin amyloidosis: not just a medical problem, but a psychosocial burden

BACKGROUND

Hereditary transthyretin (TTR) amyloidosis (ATTRv) is a heterogeneous disease with a clinical presentation that varies according to geographical area and TTR mutation. The symptoms of Val50Met-ATTRv are mainly neuropathic and progress to complete disability and death in most untreated patients within 10 to 15 years of diagnosis. The neurological effects may also be accompanied by gastrointestinal impairment, cardiomyopathy, nephropathy and/or ocular deposition. The disease is thus associated with a high degree of patient disability. Accordingly, we aimed to describe the psychosocial burden associated with ATTRv in a group of patients, asymptomatic Val50Met carriers, relatives and caregivers in the endemic focus of the disease in Majorca via a survey addressing various aspects related to psychosocial burden. We performed a an observational, descriptive, cross-sectional and multicentre study in order to analyze the prevalence of self-reported impact of ATTRv disease upon their daily life. In addition to the self-knowledge, fear and burden related to the disease. The survey was disseminated during the regular follow up at the outpatient clinic of the Hospital Universitario Son Llàtzer and during the meetings organized by the Andrade's Disease patients' advocacy group from the Balearic Islands. These meetings were attended also by subjects followed up by the Hospital Universitario Son Espases and their caregivers and relatives. Survey was self-administrated. No intervention was done by the investigators. 85 subjects completed the survey: 61 carrying the TTR-V50M variant and 24 caregivers or relatives.

RESULTS

Our study revealed that, although most of the population studied had had prior contact with ATTRv through affected relatives, there was still a lack of information regarding disease diagnosis. Fear of the genetic test result and psychological issues were common in our population. Moreover, the disease had a stronger impact on the daily life of our patients than that of our asymptomatic carriers. Autonomic symptoms were the main source of burden for relatives and caregivers.

CONCLUSION

Our survey results show high psychosocial burden associated with Val50Met-ATTRv in our area.

Real-world outcomes in non-endemic hereditary transthyretin amyloidosis with polyneuropathy: a 20-year German single-referral centre experience

BACKGROUND

Hereditary transthyretin amyloidosis is caused by pathogenic variants in the TTR gene and typically manifests, alongside cardiac and other organ dysfunctions, with a rapidly progressive sensorimotor and autonomic polyneuropathy (ATTRv-PN) leading to severe disability. While most prospective studies have focussed on endemic ATTRv-PN, real-world data on non-endemic, mostly late-onset ATTRv-PN are limited.

METHODS

This retrospective study investigated ATTRv-PN patients treated at the Amyloidosis Centre of Heidelberg University Hospital between November 1999 and July 2020. Clinical symptoms, survival, prognostic factors and efficacy of treatment with tafamidis were analysed. Neurologic outcome was assessed using the Coutinho ATTRv-PN stages, and the Peripheral Neuropathy Disability (PND) score.

RESULTS

Of 346 subjects with genetic TTR variants, 168 patients had symptomatic ATTRv-PN with 32 different TTR variants identified. Of these, 81.6% had the late-onset type of ATTRv-PN. Within a mean follow-up period of 4.1 ± 2.8 years, 40.5% of patients died. Baseline plasma N-terminal prohormone of brain natriuretic peptide (NT-proBNP) ≥900 ng/l (HR 3.259 [1.421-7.476]; p = .005) was the main predictor of mortality in multivariable analysis. 64 patients were treated with tafamidis and presented for regular follow-up examinations. The therapeutic benefit of tafamidis was more pronounced when treatment was started early in ATTRv-PN stage 1 (PND scores II vs. I; HR 2.718 [1.258-5.873]; p = .011).

CONCLUSIONS

In non-endemic, mostly late-onset ATTRv-PN, cardiac involvement assessed by NT-proBNP is a strong prognosticator for overall survival. Long-term treatment with tafamidis is safe and efficacious. Neurologic disease severity at the start of treatment is the main predictor for ATTRv-PN progression on tafamidis.

Acquired and inherited amyloidosis: Knowledge driving patients' care

Until recently, systemic amyloidoses were regarded as ineluctably disabling and life-threatening diseases. However, this field has witnessed major advances in the last decade, with significant improvements in therapeutic options and in the availability of accurate and non-invasive diagnostic tools. Outstanding progress includes unprecedented hematological response rates provided by risk-adapted regimens in light chain (AL) amyloidosis and the approval of innovative pharmacological agents for both hereditary and wild-type transthyretin amyloidosis (ATTR). Moreover, the incidence of secondary (AA) amyloidosis has continuously reduced, reflecting advances in therapeutics and overall management of several chronic inflammatory diseases. The identification and validation of novel therapeutic targets has grounded on a better knowledge of key molecular events underlying protein misfolding and aggregation and on the increasing availability of diagnostic, prognostic and predictive markers of organ damage and response to treatment. In this review, we focus on these recent advancements and discuss how they are translating into improved outcomes. Neurological involvement dominates the clinical picture in transthyretin and gelsolin inherited amyloidosis and has a significant impact on disease course and management in all patients. Neurologists, therefore, play a major role in improving patients' journey to diagnosis and in providing early access to treatment in order to prevent significant disability and extend survival.

New data on the genetic profile and penetrance of hereditary Val30Met transthyretin amyloidosis in Sweden

INTRODUCTION

Hereditary transthyretin (ATTRv) amyloidosis is of autosomal dominant transmission, caused by a spectrum of mutations in the transthyretin (TTR) gene. The ATTRV30M (p.Val50Met) is the most frequent substitution in Europe. Northern Sweden is a known cluster for ATTRV30M amyloidosis patients due to high prevalence of the mutation rate, with homozygous cases. First symptoms occur generally during the 6th decade. Previous studies reported low penetrance in this area and possible anticipation in families. In order to refine our knowledge of the genetic aspects, penetrance and factors that influence the disease's risk, we performed a comprehensive study of ATTRV30M families in Sweden.

METHODS

To assess anticipation, well-established age at onset (AO) was compared in all informative parent-offspring pairs and in subgroups, after excluding ascertainment biases. Penetrance was estimated using a non-parametric method that enables to study covariates' effect on the disease's risk.

RESULTS

We analysed 114 ATTRV30M Swedish families, including 12 homozygous individuals. Among 131 parent-offspring pairs, we found an average anticipation of 11.7 [Standard Deviation (SD) =10.03] years, higher in case of maternal transmission (mean ± SD = 13.7 ± 8.4 years), compared to paternal transmission (mean ± SD = 7.9 ± 11.5 years, p < .003). Anticipation remained significant, after exclusion of ascertainment biases. In heterozygous ATTRV30M kindred, penetrance was low, estimated below 10% [95% confidence interval (CI) = 6-10] at 40 years-old, increasing to 71% [95% CI= 65-76] at age 90 years. The risk was found to be higher in male patients (p < .01) and in case of maternal transmission (p < .01), reflecting a parent of origin effect. We observed no difference of penetrance according the geographical origin. Finally, the disease risk was similar in heterozygous and homozygous ATTRV30M amyloidosis individuals.

CONCLUSIONS

Our study provides new data on the genetics of ATTRV30M families in Sweden, including the occurrence of anticipation and on penetrance. Both are increased in case of maternal inheritance and in male patients. Overall, gender seems to be a factor that substantially modulates the AO of the disease, in this area. Clinically, these findings are of importance to guide the management of sibships and the monitoring of mutation carriers.

ATTRv in Lazio-Italy: A High-Prevalence Region in a Non-Endemic Country

Hereditary transthyretin amyloidosis (ATTRv, v for variant) prevalence in Italy, a non-endemic region, has been established by ATTRv amyloidosis Italian Registry. However, values of prevalence were extremely heterogeneous, considering different regions. To properly establish the prevalence of the disease in the Lazio region, a survey was sent to university regional hospitals and to main regional hospitals, in order to collect all affected patients regularly followed. We identified 100 ATTRv patients and, considering a Lazio population of 5.8/million, we estimated a ATTRv prevalence of 17.2/million. The ATTRv amyloidosis Italian Registry reported a prevalence of 8.0/million in Lazio, while our survey showed a value of double this. Our survey documented a high-prevalence for a non-endemic country. The increased awareness of the disease among general practitioners and medical specialists is a fundamental step to reduce the diagnostic delay and start an effective treatment of this disease.

Characteristics of Patients with Late- vs. Early-Onset Val30Met Transthyretin Amyloidosis from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is a clinically heterogeneous disease caused by mutations in the transthyretin (TTR) gene. The most common mutation, Val30Met, can manifest as an early- or late-onset disease.

METHODS

The Transthyretin Amyloidosis Outcomes Survey (THAOS) is an ongoing, global, longitudinal, observational survey of patients with transthyretin amyloidosis, including both inherited and wild-type disease and asymptomatic patients with TTR mutations. This is a descriptive analysis of symptomatic patients with ATTRv Val30Met amyloidosis with late- (age at least 50 years) vs. early-onset (age less than 50 years) disease in THAOS (data cutoff August 1, 2019).

RESULTS

Of 1389 patients with ATTRv Val30Met amyloidosis, 491 (35.3%) had late-onset disease. Compared with early-onset, patients with late-onset were more likely to be male (66.2% vs. 53.6%) and have a longer mean (standard deviation [SD]) time from onset to diagnosis (3.8 [3.4] vs. 2.7 [4.1] years). Late-onset disease was associated with more severe neurological impairment at enrollment (median [10th, 90th percentile] derived Neuropathy Impairment Score in the Lower Limbs, 25.0 [4.0, 69.3] vs. 8.0 [0, 54.8]; Neurologic Composite Score, 42.0 [2.0, 155.0] vs. 21.0 [0, 102.0]). Cardiac findings were more prominent in late-onset disease. An overall interpretation of electrocardiogram as abnormal was reported in 72.1% of late-onset patients (vs. 44.3% early-onset). A left-ventricular septal thickness of at least 12 mm was reported in 69.7% of late-onset patients (vs. 14.6% early-onset). All differences were statistically significant (p < 0.001).

CONCLUSION

In THAOS, late-onset ATTRv Val30Met amyloidosis is common, presenting with more severe neurologic and cardiac findings at enrollment. Heterogeneity of disease may make it more difficult to diagnose. Increased recognition of late-onset ATTRv Val30Met amyloidosis could lead to more timely diagnosis and improve patient outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00628745.

Very Early Onset of ATTRE89Q Amyloidosis in a Homozygous Patient

Case Presentarion:

Hereditary transthyretin amyloidosis is a progressive, fatal disease that generally involves the peripheral nervous system, the autonomic nervous system, and the heart. It is autosomal dominant with different penetrance depending on the mutation and the genetic background. Many other missense mutations of the TTR gene may cause the disease. Being an overall rare disease is very rare to observe the condition of homozygosity. In particular, cases of homozygosity have been described in patients with ATTRV30M and ATTRV122I amyloidosis. In the former, the phenotype does not seem to be aggravated, having an age of onset and disease course that does not appear to differ from those of heterozygotes, while in the latter, the onset appears to be earlier.

Conclusion:

We report the first case of ATTRE89Q amyloidosis in a patient that was homozygous for the E89Q mutation in the TTR gene. The clinical phenotype resulted in the earlier disease onset reported in this form of amyloidosis, suggesting that the homozygous condition may be prognostically negative.

Recommendations for the diagnosis and management of transthyretin amyloidosis with gastrointestinal manifestations

Transthyretin amyloid (ATTR) amyloidosis is an adult-onset, rare systemic disorder characterized by the accumulation of misfolded fibrils in the body, including the peripheral nerves, the heart and the gastrointestinal tract. Gastrointestinal manifestations are common in hereditary (ATTRv) amyloidosis and are present even before the onset of the polyneuropathy in some cases. Delays in diagnosis of ATTRv amyloidosis with gastrointestinal manifestations commonly occur because of fragmented knowledge among gastroenterologists and general practitioners, as well as a shortage of centers of excellence and specialists dedicated to disease management. Although the disease is becoming well-recognized in the societies of Neurology and Cardiology, it is still unknown for most gastroenterologists. This review presents the recommendations for ATTRv amyloidosis with gastrointestinal manifestations elaborated by a working group of European gastroenterologists and neurologists, and aims to provide digestive health specialists with an overview of crucial aspects of ATTRv amyloidosis diagnosis to help facilitate rapid and accurate identification of the disease by focusing on disease presentation, misdiagnosis and management of gastrointestinal symptoms.

Use of Drugs for ATTRv Amyloidosis in the Real World: How Therapy Is Changing Survival in a Non-Endemic Area

Background: Over the past decade, three new drugs have been approved for the treatment of hereditary amyloid transthyretin (ATTRv) polyneuropathy. The aim of this work was to analyze whether current therapies prolong survival for patients affected by ATTRv amyloidosis. Methods: The study was conducted retrospectively, analyzing the medical records of 105 patients with genetic diagnoses of familial amyloidotic polyneuropathy followed at the two referral centers for the disease in Sicily, Italy. Of these, 71 received disease-modifying therapy, while 34 received only symptomatic treatment or no therapy. Results: The most used treatment in our patient cohort was tafamidis, followed by liver transplantation, patisiran, inotersen, and diflunisal. The median survival was significantly longer for treated vs. untreated patients (12 years vs. 8 years). In the 71 patients who received disease-modifying treatment, the presence of cardiac involvement, weight loss, or autonomic dysfunction at diagnosis was not related to survival. Conversely, patients diagnosed in the early stage of the disease (PND 1) had significantly longer survival than those diagnosed in the late stage (PND 2–4).

Between responsibility and desire: Accounts of reproductive decisions from those at risk for or affected by late-onset neurological diseases

This paper explores ways in which genetic risk foregrounds forms of responsibility while dealing with reproduction. We analyzed individual and family semi-structured interviews (n = 35) with people at-risk for or affected by transthyretin-related familial amyloid polyneuropathy (TTR-FAP) and Machado-Joseph disease (MJD), which are late-onset neurological diseases. Although generally considered as rare diseases, some areas in Portugal present the world's highest frequency for MJD and TTR-FAP. Thematic analysis of the data revealed that participants drew on various - sometimes ambivalent and competing - understandings of their genetic risk and their wish to have children. Some participants perceived the avoidance of genetic risk to be responsible behavior, while, for others, responsibility entailed accepting risks because they prioritized values such as parenthood, family relationships and the value of life, above any question of genetic disease. Some participants shared accounts that were fraught with ambivalence, repentance and guilt, especially when children were born before participants knew of their own or their partner's risk. Participants' accounts also showed they make continued efforts to see themselves as responsible persons and to appear responsible in the eyes of others. We discuss findings in the context of participants' negotiation between genetic risk and their sense of responsibility toward themselves and others; we conclude that "genetic responsibility" is present not only in accounts of those who chose not to have children but also in those who make an informed decision to have at-risk children.

Psychosocial burden and professional and social support in patients with hereditary transthyretin amyloidosis (ATTRv) and their relatives in Italy

Background

Hereditary transthyretin amyloidosis (hATTR), alias ATTR variant (ATTRv) is a severe and disabling disease causing sensory and motor neuropathy, autonomic dysfunction, and cardiomyopathy. The progressive decline of patient’s functional autonomy negatively affects the patient’s quality of life and requires increasing involvement of relatives in the patient’s daily life. Family caregiving may become particularly demanding when the patient is no longer able to move independently. This study is focused on the psychosocial aspects of ATTRv from the patient and relative perspectives. In particular, it explored: the practical and psychological burdens experienced by symptomatic patients with ATTRv and their key relatives and the professional and social network support they may rely on; whether burden varied in relation to patients’ and relatives’ socio-demographic variables, patients’ clinical variables, and perceived professional and social network support; and, any difference in burden and support between patients and their matched relatives.

Methods

The study was carried out on symptomatic patients included in the ATTRv Italian national registry and living with at least one adult relative not suffering from severe illness and being free from ATTRv symptoms. Patients and relatives’ assessments were performed using validated self-reported tools.

Results

Overall, 141 patients and 69 relatives were evaluated. Constraints of leisure activities, feelings of loss and worries for the future were the consequences of ATTRv most frequently reported by patients and relatives. Both in patients and their relatives, the burden increased with the duration of symptoms and the level of help in daily activities needed by the patient. In the 69 matched patient-relative pairs, the practical burden was significantly higher among the patients than among their relatives, while the psychological burden was similar in the two groups. Moreover, compared to their relatives, patients with ATTRv reported higher levels of professional and social network support.

Conclusions

These results show that ATTRv is a disease affecting quality of life of both patients and their families. Supporting interventions should be guaranteed to patients, to facilitate their adaptation to the disease, and to their families, to cope as best as possible with the difficulties that this pathology may involve.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01812-6.

Hereditary transthyretin amyloidosis in multi-ethnic Malaysians

We report the clinical and genetic characteristics of hereditary transthyretin amyloidosis in the multi-ethnic Malaysian population. Subjects with genetically confirmed transthyretin amyloidosis seen between 2001 till August 2020 were included. There were 30 patients and 14 asymptomatic carriers, of which 26 (59.1%) were men. The majority (86.7%) were ethnic Chinese while two (6.7%) each were Malay and Sri Lankan Tamil ethnicity respectively. Among patients, mean age of symptom-onset was 55.9 ± 9.8 years with mean duration from symptom-onset to diagnosis of 3.2 ± 2.5 years. Common presenting symptoms were sensory symptoms of upper limbs (43.3%), symmetric sensory symptoms of both lower limbs (16.7%) and autonomic symptoms (16.7%). Nerve conduction studies showed sensorimotor polyneuropathy in 25 (83.3%) patients (22, axonal). Abnormal echocardiograms were seen in 24 (80%) patients, although 15 were asymptomatic. Of six different TTR mutations found, Ala97Ser was the commonest, and found exclusively in 84.6% of Chinese patients. Other mutations among Chinese patients were Val30Met, Ala25Thr and Asp39Val. Our Malay and Tamil patients had Glu54Lys and Gly47Val mutations respectively. In conclusion, TTR Ala97Ser is the commonest mutation among ethnic Chinese Malaysians which presented with late-onset progressive sensorimotor polyneuropathy, autonomic dysfunction and subclinical cardiac involvement.

Canadian Guidelines for Hereditary Transthyretin Amyloidosis Polyneuropathy Management

Hereditary transthyretin-mediated (hATTR) amyloidosis is a progressive disease caused by mutations in the TTR gene leading to multisystem organ dysfunction. Pathogenic TTR aggregation, misfolding, and fibrillization lead to deposition of amyloid in multiple body organs and frequently involve the peripheral nerve system and the heart. Common neurologic manifestations include: sensorimotor polyneuropathy (PN), autonomic neuropathy, small-fiber PN, and carpal tunnel syndrome. Many patients have significant progression due to diagnostic delays as hATTR PN is not considered within the differential diagnosis. Recently, two effective novel disease-modifying therapies, inotersen and patisiran, were approved by Health Canada for the treatment of hATTR PN. Early diagnosis is crucial for the timely introduction of these disease-modifying treatments that reduce impairments, improve quality of life, and extend survival. In this guideline, we aim to improve awareness and outcomes of hATTR PN by making recommendations directed to the diagnosis, monitoring, and treatment in Canada.

Rare variant (p.Ser43Asn) of familial transthyretin amyloidosis associated with isolated cardiac phenotype: A case series with literature review

Background

p.Ser43Asn is a very rare transthyretin (TTR) mutation leading to familial amyloidosis of transthyretin type, ATTR amyloidosis. It was previously observed in four patients worldwide and is associated almost invariably with an isolated cardiac phenotype.

Methods and Results

We report here on an Italian family with early‐onset cardiomyopathy and aggressive disease course in the affected individuals leading untreated to cardiac death before 55 years of age. We describe the clinical phenotype and imaging findings of two affected siblings, who were treated with tafamidis at an early disease stage, and their affected mother, who died 9 years ago due to refractory heart failure. The review of the available literature highlights the fact that until recently ATTR amyloidosis may have been misdiagnosed as other types of hypertrophic cardiomyopathy.

Conclusion

A better characterization of the genotype–phenotype associations is crucial to achieve optimal outcomes and facilitate informed decisions when treating individuals with rare mutations.

Clinical 3-D Gait Assessment of Patients With Polyneuropathy Associated With Hereditary Transthyretin Amyloidosis

Hereditary amyloidosis associated with transthyretin V30M (ATTRv V30M) is a rare and inherited multisystemic disease, with a variable presentation and a challenging diagnosis, follow-up and treatment. This condition entails a definitive and progressive motor impairment that compromises walking ability from near onset. The detection of the latter is key for the disease's diagnosis. The aim of this work is to perform quantitative 3-D gait analysis in ATTRv V30M patients, at different disease stages, and explore the potential of the obtained gait information for supporting early diagnosis and/or stage distinction during follow-up. Sixty-six subjects (25 healthy controls, 14 asymptomatic ATTRv V30M carriers, and 27 symptomatic patients) were included in this case-control study. All subjects were asked to walk back and forth for 2 min, in front of a Kinect v2 camera prepared for body motion tracking. We then used our own software to extract gait-related parameters from the camera's 3-D body data. For each parameter, the main subject groups and symptomatic patient subgroups were statistically compared. Most of the explored gait parameters can potentially be used to distinguish between the considered group pairs. Despite of statistically significant differences being found, most of them were undetected to the naked eye. Our Kinect camera-based system is easy to use in clinical settings and provides quantitative gait information that can be useful for supporting clinical assessment during ATTRv V30M onset detection and follow-up, as well as developing more objective and fine-grained rating scales to further support the clinical decisions.

Advances in Treatment of ATTRv Amyloidosis: State of the Art and Future Prospects

Hereditary amyloid transthyretin (ATTRv) amyloidosis with polyneuropathy is a progressive disease that is transmitted as an autosomal dominant trait and characterized by multiple organ failure, including axonal sensory-motor neuropathy, cardiac involvement, and autonomic dysfunction. Liver transplantation (LT) and combined heart-liver transplantation, introduced in the 1990s, have been the only therapies for almost two decades. In 2011, tafamidis meglumine became the first specific drug approved by regulatory agencies, since then the attention toward this disease has progressively increased and several drugs with different mechanisms of action are now available. This review describes the drugs already on the market, those that have shown interesting results although not yet approved, and those currently being tested.

Targeting transthyretin - Mechanism-based treatment approaches and future perspectives in hereditary amyloidosis

The liver-derived, circulating transport protein transthyretin (TTR) is the cause of systemic hereditary (ATTRv) and wild-type (ATTRwt) amyloidosis. TTR stabilization and knockdown are approved therapies to mitigate the otherwise lethal disease course. To date, the variety in phenotypic penetrance is not fully understood. This systematic review summarizes the current literature on TTR pathophysiology with its therapeutic implications. Tetramer dissociation is the rate-limiting step of amyloidogenesis. Besides destabilizing TTR mutations, other genetic (RBP4, APCS, AR, ATX2, C1q, C3) and external (extracellular matrix, Schwann cell interaction) factors influence the type of onset and organ tropism. The approved small molecule tafamidis stabilizes the tetramer and significantly decelerates the clinical course. By sequence-specific mRNA knockdown, the approved small interfering RNA (siRNA) patisiran and antisense oligonucleotide (ASO) inotersen both significantly reduce plasma TTR levels and improve neuropathy and quality of life compared to placebo. With enhanced hepatic targeting capabilities, GalNac-conjugated siRNA and ASOs have recently entered phase III clinical trials. Bivalent TTR stabilizers occupy both binding groves in vitro, but have not been tested in trials so far. Tolcapone is another stabilizer with the potential to cross the blood-brain barrier, but its half-life is short and liver failure a potential side effect. Amyloid-directed antibodies and substances like doxycycline aim at reducing the amyloid load, however, none of the yet developed antibodies has successfully passed clinical trials. ATTR-amyloidosis has become a model disease for pathophysiology-based treatment. Further understanding of disease mechanisms will help to overcome the remaining limitations, including application burden, side effects, and blood-brain barrier permeability.

The Clinical and Economic Burden of Newly Diagnosed Hereditary Transthyretin (ATTRv) Amyloidosis: A Retrospective Analysis of Claims Data

INTRODUCTION

Little is known about the burden of hereditary transthyretin (ATTRv) amyloidosis, a genetic, progressive, and fatal disease caused by extracellular deposition of transthyretin amyloid fibrils. The study's aim was to estimate costs and disease burden associated with ATTRv amyloidosis in a real-world setting.

METHODS

Using IBM® MarketScan® Commercial and Medicare Supplemental data, we identified patients at least 18 years of age with newly diagnosed ATTRv amyloidosis. Diagnosis required at least one medical claim with relevant diagnosis code (International Classification of Diseases, 9th Revision, Clinical Modification [ICD-9-CM] 277.30-.31, 277.39; ICD-10-CM E85.0-.4, E85.89, E85.9) between January 1, 2014 and December 31, 2016, and at least one additional criterion occurring during study period (2013-2017): at least 15 days diflunisal use without more than a 30-day gap; liver transplant; or claim with codes E85.1 or E85.2. First diagnosis date was study index. Continuous enrollment 1-year pre-index (baseline) and post-index (follow-up) was required. Patients with baseline amyloidosis diagnosis were excluded. Outcomes of interest were comorbidities and 1-year follow-up healthcare utilization and costs (also reported quarterly).

RESULTS

Among 185 qualifying patients, mean age was 59.2 years (standard deviation 15.2), 54.1% were female, and baseline Charlson comorbidity index was 2.2 (2.5). Neuropathy (30.3%), diabetes (27.0%), and cardiovascular-related comorbidities, including dyspnea (25.9%) and congestive heart failure (21.6%), were common during follow-up. Nearly a quarter of patients (24.9%) were hospitalized during follow-up. Most hospitalizations and emergency department visits occurred in the first quarter post-diagnosis (18.9%, 17.8%, respectively) and dropped in subsequent quarters. The annual mean total cost was $64,066, with inpatient services contributing the majority of the expenses ($34,461), followed by outpatient ($23,853), and then pharmacy ($5752). As with utilization, costs were highest in the first quarter post-diagnosis and dropped in subsequent quarters.

CONCLUSION

Patients newly diagnosed with ATTRv amyloidosis have substantial healthcare utilization and costs in the first year, primarily the initial months, post-diagnosis. Further research should examine later costs associated with disease progression and end-of-life care.

A Review of Patisiran (ONPATTRO®) for the Treatment of Polyneuropathy in People with Hereditary Transthyretin Amyloidosis

Hereditary variant transthyretin amyloidosis (ATTRv) is a rare genetic defect that affects about 5000-10,000 people worldwide, causing amyloidosis secondary to misfolding of mutant transthyretin (TTR) protein fibrils. TTR mutations can cause protein deposits in many extracellular regions of organs, but those deposits in cardiac and axonal cells are the primary cause of this clinical syndrome. Treatment options are limited, but new drugs are being developed. Patisiran, a novel drug, is a liposomal siRNA against TTR that specifically targets this protein, reducing the accumulation of TTR in tissues, with subsequent improvement in both neuropathy and cardiac function. Patisiran is likely to serve as a prototype for the development of further intelligent drug solutions for use in targeted therapy. In this review we summarize the evidence currently available on the treatment of polyneuropathy in people with ATTRv with patisiran. We review the evidence on its efficacy, safety, and indications of use, citing novel and seminal papers on these subjects.

ATTRv amyloidosis Italian Registry: clinical and epidemiological data

INTRODUCTION

ATTRv amyloidosis is worldwide spread with endemic foci in Portugal and Sweden, Japan, Brazil, Maiorca, and Cyprus. A national Registry was developed to characterise the epidemiology and genotype-phenotype correlation of ATTRv amyloidosis in Italy and to allow a better planning of diagnostic and therapeutic services.

METHODS

Fifteen Italian referral centres for amyloidosis spread all over the country have contributed to the Registry.

RESULTS

Four-hundred-forty-seven subjects were enrolled, 187 asymptomatic carriers and 260 affected patients. Thirty-one different mutations were recorded. The seven most represented genetic variants were significantly different in terms of age at onset, clinical features and geographical distribution. National prevalence is 4.33/million with higher values in Southern Italy. Overall symptoms of polyneuropathy were present at disease onset in about half of the patients, symptoms of cardiomyopathy in a quarter of patients, the rest referring carpal tunnel syndrome, dysautonomia or lumbar spinal stenosis. 52.6% of patients were in FAP stage 1, 20.4% in stage 2 and 13.5% in stage 3, while 13.5% patients had no neuropathy, presenting only cardiological symptoms.

CONCLUSIONS

We presented an epidemiological study based on collaboration among referral centres for ATTRv amyloidosis spread in all the Italian territory, using web-based Registry. It provided a detailed map of the regional distribution of the disease. The increased awareness of the disease among general practitioners and medical specialists has contributed to reduce the diagnostic delay and the rate of misdiagnosis. The Registry will allow to collect also future information about clinical and instrumental follow-up.

Anticipation on age at onset in kindreds with hereditary ATTRV30M amyloidosis from the Majorcan cluster

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRV30M) is a rare disease caused by amyloid deposition and characterized by a heterogeneous presentation. Anticipation (AC) is described as the decrease in age at onset (AO) within each generation. Our aim was to study AC in a large number of ATTRV30M kindred from Majorca (Spain), and gain further insight into parent-of-origin effects.

METHODS

In a cohort of 262 subjects with ATTRV30M amyloidosis belonging to 51 families, we found 37 affected pairs. AO is defined as the age at the first symptom and AC (parent's age at disease onset minus that of the offspring) were calculated. Chi-square test, independent t-test and paired t-test were used for comparisons between groups. Association between AO of parents and offsprings were assessed by Pearson's correlation coefficient.

RESULTS

Offspring mean AO was 16 years lower than that of the parents (p < .001) regardless of the sex of the parents and the offspring. AC occurred in 31 out of the 37 pairs, with no differences related to the sex of parents or offspring. There was a moderate correlation (r = 0.49; p < .001) between AO of the parents and that of the offsprings.

CONCLUSION

AC was no uncommon in our cohort, and AO tended to decrease in successive generations.

Epigenetic profiling of Italian patients identified methylation sites associated with hereditary transthyretin amyloidosis

Hereditary transthyretin (TTR) amyloidosis (hATTR) is a rare life-threatening disorder caused by amyloidogenic coding mutations located in TTR gene. To understand the high phenotypic variability observed among carriers of TTR disease-causing mutations, we conducted an epigenome-wide association study (EWAS) assessing more than 700,000 methylation sites and testing epigenetic difference of TTR coding mutation carriers vs. non-carriers. We observed a significant methylation change at cg09097335 site located in Beta-secretase 2 (BACE2) gene (standardized regression coefficient = -0.60, p = 6.26 × 10-8). This gene is involved in a protein interaction network enriched for biological processes and molecular pathways related to amyloid-beta metabolism (Gene Ontology: 0050435, q = 0.007), amyloid fiber formation (Reactome HSA-977225, q = 0.008), and Alzheimer's disease (KEGG hsa05010, q = 2.2 × 10-4). Additionally, TTR and BACE2 share APP (amyloid-beta precursor protein) as a validated protein interactor. Within TTR gene region, we observed that Val30Met disrupts a methylation site, cg13139646, causing a drastic hypomethylation in carriers of this amyloidogenic mutation (standardized regression coefficient = -2.18, p = 3.34 × 10-11). Cg13139646 showed co-methylation with cg19203115 (Pearson's r2 = 0.32), which showed significant epigenetic differences between symptomatic and asymptomatic carriers of amyloidogenic mutations (standardized regression coefficient = -0.56, p = 8.6 × 10-4). In conclusion, we provide novel insights related to the molecular mechanisms involved in the complex heterogeneity of hATTR, highlighting the role of epigenetic regulation in this rare disorder.

Neurofilament Light Chain as a Biomarker of Hereditary Transthyretin-Mediated Amyloidosis

OBJECTIVE

To identify changes in the proteome associated with onset and progression of hereditary transthyretin-mediated (hATTR) amyloidosis, also known as ATTRv amyloidosis, we performed an observational, case-controlled study that compared proteomes of patients with ATTRv amyloidosis and healthy controls.

METHODS

Plasma levels of >1,000 proteins were measured in patients with ATTRv amyloidosis with polyneuropathy who received either placebo or patisiran in a Phase 3 study of patisiran (APOLLO), and in healthy controls. The effect of patisiran on the time profile of each protein was determined by linear mixed model at 0, 9, and 18 months. Neurofilament light chain (NfL) was further assessed with an orthogonal quantitative approach.

RESULTS

Levels of 66 proteins were significantly changed with patisiran vs placebo, with NfL change most significant (p < 10^-20). Analysis of changes in protein levels demonstrated that the proteome of patients treated with patisiran trended toward that of healthy controls at 18 months. Healthy controls' NfL levels were 4-fold lower than in patients with ATTRv amyloidosis with polyneuropathy (16.3 pg/mL vs 69.4 pg/mL, effect -53.1 pg/mL [95% confidence interval -60.5 to -45.9]). NfL levels at 18 months increased with placebo (99.5 pg/mL vs 63.2 pg/mL, effect 36.3 pg/mL [16.5-56.1]) and decreased with patisiran treatment (48.8 pg/mL vs 72.1 pg/mL, effect -23.3 pg/mL [-33.4 to -13.1]) from baseline. At 18 months, improvement in modified Neuropathy Impairment Score +7 score after patisiran treatment significantly correlated with reduced NfL (R = 0.43 [0.29-0.55]).

CONCLUSIONS

Findings suggest that NfL may serve as a biomarker of nerve damage and polyneuropathy in ATTRv amyloidosis, enable earlier diagnosis of patients with ATTRv amyloidosis, and facilitate monitoring of disease progression.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that NfL levels may enable earlier diagnosis of polyneuropathy in patients with ATTRv amyloidosis and facilitate monitoring of disease progression.

Lumbar Spinal Stenosis: A Rare Presentation of Hereditary Transthyretin Amyloidosis

Hereditary transthyretin amyloidosis (hATTR) is caused by the mutations of the transthyretin (TTR) gene. Length dependent sensory-motor neuropathy with autonomic involvement is the hallmark of the disease. However, it can manifest with unusual phenotypes. A 53-year-old man presented with progressive weakness in lower limbs and operated for lumbar spinal stenosis. The progression of weakness restarted after two years with the addition of symptoms related to polyneuropathy. Electrodiagnostic studies revealed sensorimotor polyneuropathy with autonomic involvement. Sural nerve biopsy disclosed amyloid deposits. Genetic testing of TTR gene identified Glu89Gln mutation. Two years after the diagnosis, he had another decompressive surgery for lumbar spinal stenosis. Histopathological examination of ligamentum flavum specimens revealed amyloid deposits. During the follow up, he was diagnosed with laryngeal amyloidosis, which is an unusual manifestation. Seven years after the diagnosis, he died due to cardiac complications. Our patient suggested that hATTR with Glu89Gln may present with atypical symptoms. Clinicians should carefully look for hATTR in recurrent lumbar stenosis.

Abdominal fat pad biopsies exhibit good diagnostic accuracy in patients with suspected transthyretin amyloidosis

Background

The diagnostic accuracy of histopathological detection of transthyretin amyloid (ATTR) by Congo red staining of abdominal fat samples has been questioned since low sensitivity has been reported, especially for patients with ATTR cardiomyopathy. However, the outcome of surgically obtained fat pad biopsies has not yet been evaluated. The aim was to evaluate the diagnostic accuracy of skin punch biopsies from abdominal fat in patients with suspected ATTR amyloidosis.

Material and methods

Data were evaluated from patients who had undergone abdominal fat pad biopsies using a skin punch due to suspected amyloidosis from 2006 to 2015. The biopsies had been analysed using Congo red staining to determine the presence of amyloid, and immunohistochemistry or Western blot to determine the type of amyloidosis. The final diagnosis was based on the clinical picture, biopsy results and DNA sequencing. Minimum follow-up after the initial biopsy was 3 years.

Results

Two hundred seventy-four patients (61% males) were identified, and in 132 (48%), a final diagnosis of amyloidosis had been settled. The majority (93%) had been diagnosed with hereditary transthyretin (ATTRv) amyloidosis, and therefore subsequent analyses were focused on these patients. Overall, our data showed a test specificity of 99% and a sensitivity of 91%. Ninety-eight (94%) of the patients had neuropathic symptoms at diagnosis, whereas 57 (55%) had signs of amyloid cardiomyopathy. Subgroup analyses showed that patients with merely neuropathic symptoms displayed the highest test sensitivity of 91%, whereas patients with pure cardiomyopathy displayed the lowest sensitivity of 83%. However, no significant differences in sensitivity were found between patients with or without cardiomyopathy or between the sexes.

Conclusions

Abdominal fat pad biopsies exhibit good diagnostic accuracy in patients with suspect ATTRv amyloidosis, including patients presenting with cardiomyopathy. In addition, the method enables typing not only of the precursor protein but also of the amyloid fibril type, which is related to the phenotype and to the outcome of the disease.

Indirect treatment comparison of the efficacy of patisiran and inotersen for hereditary transthyretin-mediated amyloidosis with polyneuropathy

INTRODUCTION

Patisiran and inotersen are two therapies approved for the treatment of hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy, a rapidly progressive disease with a substantial clinical burden. This analysis indirectly compares the efficacy of patisiran and inotersen on neuropathy and quality of life (QOL).

METHODS

Published results from the NEURO-TTR study of inotersen and individual patient data from the APOLLO study of patisiran were used. Indirect comparisons were conducted for 15-month changes in neuropathy and QOL endpoints: modified Neuropathy Impairment Score +7 (mNIS+7_Ionis,), Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) questionnaire, body mass index (BMI), and Polyneuropathy Disability (PND) score. Analyses were conducted under different assumptions about the impact of missing data and to adjust for baseline differences between studies.

RESULTS

Patisiran showed significantly greater treatment effects than inotersen for mNIS+7_Ionis (mean difference: -12.3 [95% confidence interval: -21.4, -3.3]), Norfolk QOL-DN (-11.3 [-19.8, -2.9]), and BMI (1.0 [0.4, 1.7]). The proportion of patients with improvement or no change from baseline on PND score was higher for patisiran-treated patients (odds ratio: 8.9 [4.6, 17.5]). Results were consistent and robust across analyses and methods.

CONCLUSIONS

Patisiran demonstrated greater treatment effects on neuropathy and QOL than inotersen in patients with hATTR amyloidosis with polyneuropathy.

Quality of life outcomes in APOLLO, the phase 3 trial of the RNAi therapeutic patisiran in patients with hereditary transthyretin-mediated amyloidosis

Introduction: Hereditary transthyretin-mediated (hATTR) amyloidosis is a rare, fatal, multisystem disease leading to deteriorating quality of life (QOL). The impact of patisiran on QOL in patients with hATTR amyloidosis with polyneuropathy from the phase 3 APOLLO study (NCT01960348) is evaluated.Methods: Patients received either patisiran 0.3 mg/kg (n = 148) or placebo (n = 77) intravenously once every three weeks for 18 months. Multiple measures were used to assess varying aspects of QOL.Results: At 18 months, compared with placebo, patisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) score; (least squares [LS] mean difference: -21.1; p = 1.10 × 10^-10; improved across all domains), EuroQoL 5-dimensions 5-levels (LS mean difference: 0.2; p = 1.4 × 10^-12), EuroQoL-visual analog scale (LS mean difference: 9.5; p=.0004), Rasch-built Overall Disability Scale (LS mean difference: 9.0; p = 4.07 × 10^-16) and Composite Autonomic Symptom Score-31(COMPASS-31; LS mean difference: -7.5; p=.0008). Placebo-treated patients experienced rapid QOL deterioration; treatment effects for patisiran were observed as early as 9 months. At 18 months, patisiran improved Norfolk QOL-DN total score and three individual domains as well as COMPASS-31 total scores relative to baseline. Consistent benefits were also observed in the cardiac subpopulation.Conclusion: The benefits of patisiran across all QOL measures and the rapid deterioration observed with placebo, highlight the urgency in early treatment for patients with hATTR amyloidosis with polyneuropathy.

Cardiac involvement, morbidity and mortality in hereditary transthyretin amyloidosis because of p.Glu89Gln mutation

BACKGROUND

Hereditary transthyretin amyloidosis is a systemic infiltrative disease, caused by a mutation in the transthyretin gene. p.Glu89Gln is the most common mutation in the Balkan countries.

METHODS

We evaluated the clinical manifestations, cardiac involvement, morbidity and mortality in 78 patients with p.Glu89Gln mutation, verified through a DNA analysis. Clinical assessment, electrocardiogram and echocardiography were performed at the time of diagnosis. The patients have been followed for 30 months.

RESULTS

All included patients were Caucasian, 39 (50%) - men, with median age at diagnosis of 56 years (42-73), median age at onset -- 53 years (35-69), starting significantly earlier in men (4.36, P = 0.004). Cardiac and neurological involvement was found in 74 (95%) patients. Pathological ECG was present in 65 (84%) patients, infarct pattern in 43 (56%), low voltage in 24 (31%). Echocardiography revealed an infiltrative cardiomyopathy with restrictive filling in 31 (40%) and ejection fraction less than 50% in 20 (27%) patients. Twenty-two patients (28%) died: 14 (64%) because of advanced heart failure, 6 (27%) died suddenly, 2 (9%) from an ischemic stroke. The median age at death was 58.5 years (52-72). No statistically significant sex difference in survival was observed; a significant difference in survival was found for the New York Heart Association class, familial amyloidotic polyneuropathy stage, ejection fraction, filling pattern and tafamidis treatment.

CONCLUSION

Cardiac involvement is common and has significant prognostic implications in the evaluated patients with p.Glu89Gln mutation. Heart failure and rhythm disturbances are the main causes of death. An earlier identification of the disease is crucial to improve prognosis.

Hereditary ATTR Amyloidosis in Austria: Prevalence and Epidemiological Hot Spots

BACKGROUND

Hereditary transthyretin amyloidosis (hATTR) is an autosomal dominantly inherited disorder caused by an accumulation of amyloid fibrils in tissues due to mutations in the transthyretin (TTR) gene. The prevalence of hATTR is still unclear and likely underestimated in many countries. In order to apply new therapies in a targeted manner, early diagnosis and knowledge of phenotype-genotype correlations are mandatory. This study aimed to assess the prevalence and phenotypic spectrum of hATTR in Austria.

METHODS

Within the period of 2014-2019, patients with ATTR-associated cardiomyopathy and/or unexplained progressive polyneuropathies were screened for mutations in the TTR gene.

RESULTS

We identified 43 cases from 22 families carrying 10 different TTR missense mutations and confirmed two mutational hot spots at c.323A>G (p.His108Arg) and c.337G>C (p.Val113Leu). Two further patients with late onset ATTR carried TTR variants of unknown significance. The majority of patients initially presented with heart failure symptoms that were subsequently accompanied by progressive polyneuropathy in most cases. A total of 55% had a history of carpal tunnel syndrome before the onset of other organ manifestations.

CONCLUSIONS

Our study underlined the relevance of hATTR in the pathogenesis of amyloid-driven cardiomyopathy and axonal polyneuropathy and indicated considerable genetic heterogeneity of this disease in the Austrian population. The estimated prevalence of hATTR in Austria based on this study is 1:200,000 but a potentially higher number of unknown cases must be taken into account. With respect to new therapeutic approaches, we strongly propose genetic testing of the TTR gene in an extended cohort of patients with unexplained heart failure and progressive polyneuropathy.

Overview of treatments used in transthyretin-related hereditary amyloidosis: a systematic review

OBJECTIVE

To carry out a systematic review of the literature to analyse the efficacy and safety of treatments available or under investigation for amyloidosis due to mutations in the transthyretin gene (ATTR).

METHODS

A bibliographic search was carried out in the following electronic databases up to September 2017: PubMed, Cochrane Library and EMBASE. The inclusion criteria were: efficacy and/or safety studies conducted in humans, studies that included treatments, including treatments in the research phase, and studies that included 10 or more patients.

RESULTS

A total of 21 articles were included; 16 were clinical trials, eight of them (50%) phase III trials, and five were observational studies. Of the total number of studies selected, 11 were on tafamidis, four on diflunisal, two on liver transplantation, two on patisiran and two on other therapeutic alternatives. Of the 11 studies related to the drug, the pivotal trial, the results of its two extension studies and an additional post hoc analysis were selected. In addition, two phase III trials were included in specific populations, two phase II studies, one safety study and two observational studies. Regarding the four included studies related to the drug, one was the pivotal trial that gave the indication to diflunisal, another a safety summary of the pivotal trial, and the other two trials were carried out in specific populations, one in a Japanese population and another phase I trial in cardiac amyloidosis in the USA. As far as other alternatives are concerned, of the six studies included in this section, two were related to liver transplantation, two to patisiran and two to different therapeutic alternatives.

CONCLUSIONS

Sufficient evidence has not been found that demonstrates superiority among the available oral alternatives, diflunisal or tafamidis, in the treatment of ATTR. Direct comparisons between both drugs and pharmacoeconomic studies would be necessary to select the most efficient treatment.

Transthyretin amyloidosis: Testing strategies and model for center of excellence support

Appropriate testing strategies and strict model for Center Of Excellence (CoE) support are essential for the correct diagnosis, follow-up strategy and treatment plan for transthyretin (ATTR) amyloidosis. CoE is defined as a programme within a healthcare institution established to provide an exceptionally high concentration of expertise and related resources centred on a particular area of medicine, delivering associated care in a comprehensive, interdisciplinary fashion to afford the best patient outcome. Ideally, CoEs provide regular education and training for healthcare professionals and share knowledge and learning with other CoEs and specialists to ensure the highest standards of care. CoEs and testing strategies are of significant value to those with rare diseases and their families, as there is naturally low awareness among healthcare professionals, a phenomenon that potentially delays diagnosis and treatment. In this review, we focus on the importance of performing the most appropriate testing strategies for ATTR amyloidosis and establishing a CoE for this rare disease. We highlight our experience in establishing a CoE in Sofia, Bulgaria and define the fundamental steps needed to successfully launch a programme.

TTR-FAP Progression Evaluation Based on Gait Analysis Using a Single RGB-D Camera

Transthyretin Familial Amyloid Polyneuropathy (TTR-FAP) is a rare and disabling neurological disorder caused by a mutation of the transthyretin gene. One of the disease's characteristics that mostly affects patients' quality of life is its influence on locomotion, with a variable evolution timing. Quantitative motion analysis is useful for assessing motor function, including gait, in diseases affecting movement. However, it is still an evolving field, especially in TTR-FAP, with only a few available studies. A single markerless RGB-D camera provides 3-D body joint data in a less expensive, more portable and less intrusive way than reference multi-camera marker-based systems for motion capture. In this contribution, we investigate if a gait analysis system based on a RGB-D camera can be used to detect gait changes over time for a given TTR-FAP patient. 3-D data provided by that system and a reference system were acquired from six TTR-FAP patients, while performing a simple gait task, once and then a year and a half later. For each gait cycle and system, several gait parameters were computed. For each patient, we investigated if the RBG-D camera system is able to detect the existence or not of statistically significant differences between the two different acquisitions (separated by 1.5 years of disease evolution), in a similar way to the reference system. The obtained results show the potential of using a single RGB-D camera to detect relevant changes in spatiotemporal gait parameters (e.g., stride duration and stride length), during TTR-FAP patient follow-up.

TTRMDB: A database for structural and functional analysis on the impact of SNPs over transthyretin (TTR) using bioinformatic tools

Hereditary Transthyretin-associated amyloidosis (ATTR) is an autosomal dominant protein-folding disorder with adult-onset caused by mutation of transthyretin (TTR). TTR is characterized by extracellular deposition of amyloid, leading to loss of autonomy and finally, death. More than 100 distinct mutations in TTR gene have been reported from variable age of onset, clinical expression and penetrance data. Besides, the cure for the disease remains still obscure. Further, the prioritizing of mutations concerning the characteristic features governing the stability and pathogenicity of TTR mutant proteins remains unanswered, to date and thus, a complex state of study for researchers. Herein, we provide a full report encompassing the effects of every reported mutant model of TTR protein about the stability, functionality and pathogenicity using various computational tools. In addition, the results obtained from our study were used to create TTRMDB (Transthyretin mutant database), which could be easy access to researchers at http://vit.ac.in/ttrmdb.

The Pathology of Amyloidosis in Classification: A Review

BACKGROUND

The amyloidoses are a rare and heterogeneous group of disorders that are characterized by the deposition of abnormally folded proteins in tissues ultimately leading to organ damage. The deposits are mainly extracellular and are recognizable by their affinity for Congo red and their yellow-green birefringence under polarized light. Current classification of amyloid in medical practice is based on the amyloid protein type. To date, 36 proteins have been identified as being amyloidogenic in humans.

SUMMARY

in clinical practice, it is critical to distinguish between treatable versus non-treatable amyloidoses. Moreover, amyloidoses with a genetic component must be distinguished from the sporadic types and systemic amyloidoses must be distinguished from the localized forms. Among the systemic amyloidoses, AL continues to be the most common amyloid diagnosis in the developed world; other clinically significant types include AA, ALECT2, and ATTR. The latter is emerging as an underdiagnosed type in both the hereditary and wild-type setting. Other hereditary amyloidoses include AFib, several amyloidoses derived from apolipoproteins, AGel, ALys, etc. In a dialysis setting, systemic amyloid derived from β2 microglobulin (Aβ2M) should be considered, although a very rare hereditary variant has also been reported; several amyloidoses may be typically associated with aging and several iatrogenic types have also emerged. Determination of the amyloid protein type is imperative before specific therapy can be implemented and the current methods are briefly summarized. A brief overview of the target organ involvement by amyloid type is also included. Key Messages: (1) Early diagnosis of amyloidosis continues to pose a significant challenge and requires the participation of many clinical and laboratory specialties. (2) Determination of the protein type is imperative before specific therapy can be implemented. (3) While mass spectrometry has emerged as the preferred method of amyloid typing, careful application of immune methods is still clinically useful but caution and experience, as well as awareness of the limitations of each method, are necessary in their interpretation. (4) While the spectrum of amyloidoses continues to expand, it is critical to distinguish between those that are currently treatable versus those that are untreatable and avoid causing harm by inappropriate treatment.