Recommendations for presymptomatic genetic testing and management of individuals at risk for hereditary transthyretin amyloidosis

Standard Therapy in Cardiac Amyloidosis: What is Known, What is "Gray"

Amyloidosis is a systemic disease due to the accumulation of misfolded amyloid fibrils that damage the heart and worsen the prognosis. Heart failure (HF), a condition frequently linked with an advanced stage of this disease, is the most prevalent clinical manifestation that leads to its diagnosis. However, due to the growing awareness of the occurrence of cardiac amyloidosis (CA), it is now possible to perform an early diagnosis and have a positive impact on its natural course. This study aims to highlight the most compelling issues concerning patients' clinical management with HF and CA.

Value of multi-modality small fiber assessments in a genotypically diverse cohort of transthyretin-related amyloidosis in the early stages of disease

INTRODUCTION

Transthyretin-related amyloidosis (ATTRv) is a progressive multisystem disorder, predominantly involving the peripheral nerve system (PNS) and heart. Quantification of small fiber damage may help guide treatment decisions, as amyloid deposits frequently affect those fibers early in disease course. Corneal confocal microscopy (CCM) is a promising method to monitor patients with ATTRv, due to similarities between corneal nerves and PNS, as the cornea is innervated by Aδ and C fibers.

METHODS

We compared CCM measures from ATTRv patients to a group of healthy individuals, matched by age and gender. We then investigated the correlations between small fiber tests (SFT): CCM, LDI-Flare and CDT, COMPASS-31 and disability scales (RODS and ONLS) in patients.

RESULTS

Of 20 patients (6 with V30M), mean age 50.3±15.3Y, 7 female (35%), six (30%) had polyneuropathy and 10 (50%) carpal tunnel syndrome. CDT was abnormal in 9 and LDI-flare in 6 patients. CCM was abnormal in 19 tested patients and significantly reduced when compared to controls (CNFL: 6.31±0.31 vs. 15.21±1.02mm/mm2, p<0.001). Mean COMPASS-31-scores were 22.27±22.84; RODS and ONLS were 38.15±12.33 and 2.05±2.3, with no significant differences between sub-group scores. Disease duration was significantly correlated with ONLS (0.43, p=0.05) and RODS (0.46, p=0.03). There were no significant correlations between measures of disability and SFT.

CONCLUSIONS

In a diverse cohort of ATTRv patients, CCM was the most frequent abnormal measurement. CCM can be a useful test to triage patients in the early disease stages and with few or equivocal symptoms.

Longitudinal analysis of serum neurofilament light chain levels as marker for neuronal damage in hereditary transthyretin amyloidosis

OBJECTIVE

To evaluate serum neurofilament light chain (sNfL) as biomarker of disease onset, progression and treatment effect in hereditary transthyretin (ATTRv) amyloidosis patients and TTR variant (TTRv) carriers.

METHODS

sNfL levels were assessed longitudinally in persistently asymptomatic TTRv carriers (N = 12), persistently asymptomatic ATTRv amyloidosis patients (defined as asymptomatic patients but with amyloid detectable in subcutaneous abdominal fat tissue) (N = 8), in TTRv carriers who developed polyneuropathy (N = 7) and in ATTRv amyloidosis patients with polyneuropathy on treatment (TTR-stabiliser (N = 20) or TTR-silencer (N = 18)). Polyneuropathy was confirmed by nerve conduction studies or quantitative sensory testing. sNfL was analysed using a single-molecule array assay.

RESULTS

sNfL increased over 2 years in persistently asymptomatic ATTRv amyloidosis patients, but did not change in persistently asymptomatic TTRv carriers. In all TTRv carriers who developed polyneuropathy, sNfL increased from 8.4 to 49.8 pg/mL before the onset of symptoms and before polyneuropathy could be confirmed neurophysiologically. In symptomatic ATTRv amyloidosis patients on a TTR-stabiliser, sNfL remained stable over 2 years. In patients on a TTR-silencer, sNfL decreased after 1 year of treatment.

CONCLUSION

sNfL is a biomarker of early neuronal damage in ATTRv amyloidosis already before the onset of polyneuropathy. Current data support the use of sNfL in screening asymptomatic TTRv carriers and in monitoring of disease progression and treatment effect.

Genetic counselling for at-risk family members with hereditary transthyretin amyloidosis: data from a single-centre study

BACKGROUND

Hereditary transthyretin-related amyloidosis is an autosomal dominant disorder. Recently, disease-modifying therapies (DMTs) have been developed. For at-risk individuals, genetic analysis aids in the early administration of medical care; however, few studies have evaluated the current status of genetic counselling and management of presymptomatic carriers of amyloidogenic variants.

METHODS

We retrospectively evaluated the medical records of 202 consecutive participants.

RESULTS

A total of 103 clients who received genetic counselling for predictive testing were at-risk, and 83 underwent predictive testing. Genetic testing results were positive in 33 patients, 11 of whom had confirmed amyloid deposition and were administered DMTs. For presymptomatic V30M (p.V50M) carriers, 32.0 ± 2.4 years (median ± standard error) was the age when amyloid deposition was first identified (95% confidence interval 27.4-36.6). Serum transthyretin (TTR) levels decreased serially with an estimated slope of -1.2 mg/dL/year.

CONCLUSIONS

Our study suggests the clinical utility of management using a combination of predictive testing and monitoring methods. Psychosocial support should be considered with collaboration between geneticists/genetic counsellors and psychologists. For a more optimised protocol for monitoring and designing future interventional trials in presymptomatic carriers, prospective cohort studies are necessary to clarify the natural history, particularly in the early stages of the disease.

Detailed clinical, physiological and pathological phenotyping can impact access to disease-modifying treatments in ATTR carriers

BACKGROUND

Hereditary transthyretin amyloidosis is a life-threatening autosomal dominant systemic disease due to pathogenic TTR variants (ATTRv), mostly affecting the peripheral nerves and heart. The disease is characterised by a combination of symptoms, organ involvement and histological amyloid deposition. The available disease-modifying ATTRv treatments (DMTs) are more effective if initiated early. Pathological nerve conduction studies (NCS) results are the cornerstone of large-fibre polyneuropathy diagnosis, but this anomaly occurs late in the disease. We investigated the utility of a multimodal neurological and cardiac evaluation for detecting early disease onset in ATTRv carriers.

METHODS

We retrospectively analysed a cohort of ATTRv carriers with normal NCS results regardless of symptoms. Multimodal denervation and infiltration evaluations included a clinical questionnaire (Lauria and New York Heart Association (NYHA)) and examination, intra-epidermal nerve fibre density assessment, autonomic assessment based on heart rate variability, Sudoscan, meta-iodo-benzyl-guanidine scintigraphy, cardiac biomarkers, echocardiography, MRI and searches for amyloidosis on skin biopsy and bone scintigraphy.

RESULTS

We included 130 ATTRv carriers (40.8% men, age: 43.6±13.5 years), with 18 amyloidogenic TTR gene mutations, the majority of which was the late-onset Val30Met variant (42.3%). Amyloidosis was detected in 16.9% of mutation carriers, including 9 (6.9%) with overt disease (Lauria>2 or NYHA>1) and 13 asymptomatic carriers (10%) with organ involvement (small-fibre neuropathy or cardiomyopathy). Most of these patients received DMT. Abnormal test results of unknown significance were obtained for 105 carriers (80.8%). Investigations were normal in only three carriers (2.3%).

CONCLUSIONS

Multimodal neurological and cardiac investigation of TTRv carriers is crucial for the early detection of ATTRv amyloidosis and initiation of DMT.

Early detection of nerve involvement in presymptomatic TTR mutation carriers: exploring potential markers of disease onset

BACKGROUND

Hereditary transthyretin (ATTRv) amyloidosis is a heterogeneous, progressive, multisystemic disease with a life-threatening course if left untreated. Given the current availability of effective therapies, close follow-up of presymptomatic TTR mutation carriers is essential to recognize disease onset at the earliest sign. In addition to routine techniques, in recent years several novel tools have been proposed, although a consensus on their use has not been reached yet. In this paper, we aimed to evaluate possible markers of neuropathic disease onset intended to discriminate clinically asymptomatic carriers from early symptomatic patients, thus allowing timely treatment initiation.

METHODS

Thirty-eight presymptomatic carriers were enrolled. Clinical and electrophysiological findings at first evaluation and follow-up were collected. All carriers underwent an extensive clinical and instrumental evaluation according to the standard clinical practice. One or more non-routine investigations, whose use in this field is not yet validated (henceforth "unconventional"), were additionally assessed in a subgroup of individuals.

RESULTS

Based on the exclusive use of routine investigations, it was possible to define disease onset in 4/38 carriers during the follow-up. Employing additionally one or more "unconventional" tests, abnormal findings, indicative of a possible "conversion" to symptomatic disease, were detected in further 12 cases. More than half of our study cohort showed findings suggestive of small nerve fiber (SF) involvement at either invasive or non-invasive tests.

CONCLUSIONS

A close, multidisciplinary monitoring of presymptomatic TTR mutation carriers is fundamental, and diagnostic workup should include both routine and "unconventional" tests. Assessment of SF involvement is important also in non-endemic countries.

Treatment response and neurofilament light chain levels with long-term patisiran in hereditary transthyretin-mediated amyloidosis with polyneuropathy: 24-month results of an open-label extension study

BACKGROUND

Longitudinal changes in neurofilament light chain (NfL) levels were evaluated alongside prespecified clinical assessments 24 months into the patisiran Global open-label extension (OLE) study in patients with ATTRv amyloidosis with polyneuropathy.

METHODS

All patients enrolled in the Global OLE, from phase III APOLLO and phase II OLE parent studies, received patisiran. Assessments included measures of polyneuropathy (modified Neuropathy Impairment Score+7 (mNIS+7)), quality of life (QOL; Norfolk QOL-Diabetic Neuropathy questionnaire (Norfolk QOL-DN)), and plasma NfL.

RESULTS

Patients receiving patisiran in the parent study (APOLLO-patisiran, n = 137; phase II OLE-patisiran, n = 25) demonstrated sustained improvements in mNIS+7 (mean change from parent study baseline (95% confidence interval): APOLLO-patisiran -4.8 (-8.9, -0.6); phase II OLE-patisiran -5.8 (-10.5, -1.2)) and Norfolk QOL-DN (APOLLO-patisiran -2.4 (-7.2, 2.3)), and maintained reduced NfL levels at Global OLE 24 months. After initiating patisiran in the Global OLE, APOLLO-placebo patients (n = 49) demonstrated stabilized mNIS+7, improved Norfolk QOL-DN, and significantly reduced NfL levels. Patisiran continued to demonstrate an acceptable safety profile. Earlier patisiran initiation was associated with a lower exposure-adjusted mortality rate.

CONCLUSIONS

Long-term patisiran treatment led to sustained improvements in neuropathy and QOL, with NfL demonstrating potential as a biomarker for disease progression and treatment response in ATTRv amyloidosis with polyneuropathy.

High-Sensitivity Cardiac Troponin T to Exclude Cardiac Involvement in TTR Variant Carriers and ATTRv Amyloidosis Patients

(1) Background: Individuals carrying a pathogenic transthyretin gene variant (TTRv) are at high risk for developing hereditary transthyretin (ATTRv) amyloidosis and are routinely screened for the development of cardiomyopathy (ATTRv-CM). This study aims to evaluate whether the cardiac biomarkers N-terminal pro B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) can be used to rule out ATTRv-CM. (2) Methods: In this retrospective case-control study, data from 46 ATTRv-CM patients and 101 TTRv carriers and ATTRv amyloidosis patients without cardiomyopathy were included. Binary logistic regression models were used to assess the ability of NT-proBNP and hs-cTnT to predict the diagnosis of ATTRv-CM. An optimal cutoff for the relevant biomarker(s) was determined based on a sensitivity of ≥99% and the highest possible percentage of additional tests avoided (%ATA) in the index dataset. (3) Results: Hs-cTnT demonstrated the highest predictive capabilities for ATTRv-CM. The addition of NT-proBNP did not improve the predictive model. A hs-cTnT cutoff of <6 ng/L resulted in a 97% sensitivity and a negative predictive value of 95% with a %ATA of 30% in the validation dataset. (4) Conclusion: In conclusion, hs-cTnT is a useful biomarker for excluding cardiac involvement in TTRv carriers and ATTRv amyloidosis patients and it has the potential to prevent unnecessary diagnostic procedures.

Advances in the diagnosis and treatment of transthyretin amyloid cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underrecognized cause of heart failure (HF). ATTR-CM can lead to a number of cardiovascular manifestations including HF, rhythm disturbances, and valvular disease that ultimately limit quality of life and prognosis. Due to advances in diagnostic modalities and therapeutic options, the prevalence of ATTR-CM is rising. There are several classes of medications under active investigation, though most therapies are most efficacious if instituted early on in the disease course. As such, early clinical recognition and prompt diagnosis are crucial to improving disease related outcomes. In this review, we highlight clinical manifestations of ATTR-CM as well as contemporary diagnostic and treatment approaches to the disease.

Utility of Genetic Testing in Patients with Transthyretin Amyloid Cardiomyopathy: A Brief Review

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an increasingly diagnosed condition. Although wild-type transthyretin amyloidosis (ATTRwt) is the most common ATTR-CM, hereditary transthyretin amyloidosis (ATTRv) may also occur. Currently, genetic testing for transthyretin pathogenic variants is recommended for patients with a confirmed clinical diagnosis of ATTR-CM. In fact, confirmation of this autosomal dominant pathogenic variant prompts genetic counselling and allows early identification of affected relatives. Additionally, in the presence of an ATTR-CM-associated polyneuropathy, specific drugs targeting transthyretin can be used. In this paper, we review the utility of genetic testing for the detection of pathogenic variants among patients harboring ATTR-CM and its impact on the natural history of the disease.

Optimal practices for the management of hereditary transthyretin amyloidosis: real-world experience from Japan, Brazil, and Portugal

Hereditary transthyretin (ATTRv) amyloidosis is a rare and autosomal dominant disorder associated with mutations in the transthyretin gene. Patients present with diverse symptoms related to sensory, motor, and autonomic neuropathy, as well as gastrointestinal, ocular, cardiac, renal and orthopedic symptoms, resulting from the deposition of transthyretin amyloid fibrils in multiple organs. The progressive nature of ATTRv amyloidosis necessitates pre- and post-onset monitoring of the disease. This review article is primarily based on a collation of discussions from a medical advisory board meeting in August 2021. In this article, we summarize the best practices in amyloidosis centers in three major endemic countries for ATTRv amyloidosis (Japan, Brazil, and Portugal), where most patients carry the Val30Met mutation in the transthyretin gene and the patients' genetic background was proven to be the same. The discussions highlighted the similarities and differences in the management of asymptomatic gene mutation carriers among the three countries in terms of the use of noninvasive tests and tissue biopsies and timing of starting the investigations. In addition, this article discusses a set of practical tests and examinations for monitoring disease progression applicable to neurologists working in diverse medical settings and generalizable in non-endemic countries and areas. This set of assessments consists of periodic (every 6 to 12 months) evaluations of patients' nutritional status and autonomic, renal, cardiac, ophthalmologic, and neurological functions. Physical examinations and patient-reported outcome assessments should be also scheduled every 6 to 12 months. Programs for monitoring gene mutation carriers and robust referral networks can aid in appropriate patient management in pre- to post-onset stages. For pre- and post-symptom onset testing for ATTRv amyloidosis, various noninvasive techniques are available; however, their applicability differs depending on the medical setting in each country and region, and the optimal option should be selected in view of the clinical settings, medical environment, and available healthcare resources in each region.

Hereditary transthyretin amyloidosis: a comprehensive review with a focus on peripheral neuropathy

Amyloidoses represent a group of diseases characterized by the pathological accumulation in the extracellular area of insoluble misfolded protein material called "amyloid". The damage to the tissue organization and the direct toxicity of the amyloidogenic substrates induce progressive dysfunctions in the organs involved. They are usually multisystem diseases involving several vital organs, such as the peripheral nerves, heart, kidneys, gastrointestinal tract, liver, skin, and eyes. Transthyretin amyloidosis (ATTR) is related to abnormalities of transthyretin (TTR), a protein that acts as a transporter of thyroxine and retinol and is produced predominantly in the liver. ATTR is classified as hereditary (ATTRv) and wild type (ATTRwt). ATTRv is a severe systemic disease of adults caused by mutations in the TTR gene and transmitted in an autosomal dominant manner with incomplete penetrance. Some pathogenic variants in TTR are preferentially associated with a neurological phenotype (progressive peripheral sensorimotor polyneuropathy); others are more frequently associated with restrictive heart failure. However, many mutations express a mixed phenotype with neurological and cardiological involvement. ATTRv is now a treatable disease. A timely and definite diagnosis is essential in view of the availability of effective therapies that have revolutionized the management of affected patients. The purpose of this review is to familiarize the clinician with the disease and with the correct diagnostic pathways in order to obtain an early diagnosis and, consequently, the possibility of an adequate treatment.

Quantification of muscle involvement in familial amyloid polyneuropathy using MRI

BACKGROUND AND PURPOSE

Transthyretin familial amyloid polyneuropathy (TTR-FAP) is a rare genetic disease with autosomal-dominant inheritance. In this study, we aimed to quantify fatty infiltration (fat fraction [FF]) and magnetization transfer ratio (MTR) in individual muscles of patients with symptomatic and asymptomatic TTR-FAP using magnetic resonance imaging. Secondarily, we aimed to assess correlations with clinical and electrophysiological variables.

METHODS

A total of 39 patients with a confirmed mutation in the TTR gene (25 symptomatic and 14 asymptomatic) and 14 healthy volunteers were included. A total of 16 muscles were manually delineated in the nondominant lower limb from T1-weighted anatomical images. The corresponding masks were propagated on the MTR and FF maps. Detailed neurological and electrophysiological examinations were conducted in each group.

RESULTS

The MTR was decreased (42.6 AU; p = 0.001) and FF was elevated (14%; p = 0.003) in the lower limbs of the symptomatic group, with preferential posterior and lateral involvement. In the asymptomatic group, elevated FF was quantified in the gastrocnemius lateralis muscle (11%; p = 0.021). FF was significantly correlated with disease duration (r = 0.49, p = 0.015), neuropathy impairment score for the lower limb (r = 0.42, p = 0.041), Overall Neuropathy Limitations Scale score (r = 0.49, p = 0.013), polyneuropathy disability score (r = 0.57, p = 0.03) and the sum of compound muscle action potential (r = 0.52, p = 0.009). MTR was strongly correlated to FF (r = 0.78, p < 0.0001), and a few muscles with an FF within the normal range had a reduced MTR.

CONCLUSION

These observations suggest that FF and MTR could be interesting biomarkers in TTR-FAP. In asymptomatic patients, FF in the gastrocnemius lateralis muscle could be a good indicator of the transition from an asymptomatic to a symptomatic form of the disease. MTR could be an early biomarker of muscle alterations.

Changes in amyloidosis phenotype over 11 years in a cardiac amyloidosis referral centre cohort in France

BACKGROUND

Early cardiac amyloidosis (CA) diagnosis enables patients to access effective treatments for better long-term outcomes, yet it remains under-recognised, misdiagnosed and inadequately managed.

AIM

To reduce diagnostic delays, we aimed to describe the epidemiological and clinical characteristics and changes over an 11-year period.

METHODS

This was a retrospective, observational cohort study of all patients referred to the Henri-Mondor Hospital for suspected CA.

RESULTS

Overall, 3194 patients were identified and 3022 were included and analysed. Our patients came from varied ethnic backgrounds, and more than half (55.2%) had confirmed CA. Over 11 years, referrals increased 4.4-fold, mostly from cardiologists. Notably, wild-type transthyretin amyloidosis (ATTRwt) became the predominant diagnosis, with referrals increasing 15-fold from 20 in 2010-2012 to 308 in 2019-2020. The number of amyloid light chain (AL) diagnoses increased, whilst variant transthyretin amyloidosis (ATTRv) numbers remained relatively stable. Concerning disease severity, AL patients presented more frequently with severe cardiac involvement whereas an increasing number of ATTRwt patients presented with National Amyloid Centre stage I (22.0% in 2013-2014 to 45.9% in 2019-2020). Lastly, among patients diagnosed with ATTRv in 2019-2020, 83.9% had ATTR Val122Ile cardiac phenotype.

CONCLUSIONS

This study shows that increasing cardiologist awareness and referrals have increased CA diagnoses. With improved awareness and non-invasive diagnostic techniques, more patients with ATTRwt with milder disease and more ATTRv Val122Ile mutations are being referred and diagnosed. Although more AL cases are being recognised, patients are diagnosed with severe cardiac involvement.

Consensus recommendations on holistic care in hereditary ATTR amyloidosis: an international Delphi survey of patient advocates and multidisciplinary healthcare professionals

BACKGROUND

Hereditary transthyretin-mediated amyloidosis is a rare, progressive and potentially life-limiting multisystem disease, affecting every aspect of a patient's life.

OBJECTIVES

This online international Delphi survey aimed to evolve clinical-patient-led practical guidance, to inspire and encourage a holistic approach to care that is managed in specialist settings by multidisciplinary teams and supported by allied healthcare professionals (HCPs) and patient advocacy groups (PAGs).

DESIGN

A 14-member joint patient advocate-HCP primary panel was convened including representation from PAGs and key clinical specialties (neurology, cardiology, internal medicine, physiotherapy, clinical psychology, dietetics and specialist nursing). Guidance evolved on the care provision needed to support seven core goals: early diagnosis and treatment; disease monitoring and organisation of care; maintenance of physical and mental health; family-centred care and caregiver support; patient-doctor dialogue; access to social support and social networking.

PARTICIPANTS

From June to October 2022, 252 HCPs and 51 PAG representatives from 27 countries were invited to participate in a Delphi survey. Of the 122 respondents who answered at least one survey question, most were HCPs (100, 82%) from specialist centres; the remainder were PAG representatives (22, 18%).

MAIN OUTCOME MEASURE

Both level of agreement and feasibility in practice of each recommendation was tested by two anonymised online Delphi voting rounds.

RESULTS

Based on an a priori threshold for consensus of ≥75% agreement, the clinical-patient community endorsed all but one recommendation. However, only 17/49 (35%) recommendations were identified by most HCPs as a core part of routine care; the remainder (32/49 (65%)) were identified as part of core care by <50% of HCPs respondents, or as largely achievable by 30%-45% of HCPs. By comparison, PAGs recorded lower implementation levels.

CONCLUSIONS

Further consideration is needed on how to evolve multidisciplinary services (supported by allied HCPs and PAGs) to address the complex needs of those affected by this disease.

Clinical model for Hereditary Transthyretin Amyloidosis age of onset prediction

Introduction

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is a rare neurological hereditary disease clinically characterized as severe, progressive, and life-threatening while the age of onset represents the moment in time when the first symptoms are felt. In this study, we present and discuss our results on the study, development, and evaluation of an approach that allows for time-to-event prediction of the age of onset, while focusing on genealogical feature construction.

Materials and methods

This research was triggered by the need to answer the medical problem of when will an asymptomatic ATTRv patient show symptoms of the disease. To do so, we defined and studied the impact of 77 features (ranging from demographic and genealogical to familial disease history) we studied and compared a pool of prediction algorithms, namely, linear regression (LR), elastic net (EN), lasso (LA), ridge (RI), support vector machines (SV), decision tree (DT), random forest (RF), and XGboost (XG), both in a classification as well as a regression setting; we assembled a baseline (BL) which corresponds to the current medical knowledge of the disease; we studied the problem of predicting the age of onset of ATTRv patients; we assessed the viability of predicting age of onset on short term horizons, with a classification framing, on localized sets of patients (currently symptomatic and asymptomatic carriers, with and without genealogical information); and we compared the results with an out-of-bag evaluation set and assembled in a different time-frame than the original data in order to account for data leakage.

Results

Currently, we observe that our approach outperforms the BL model, which follows a set of clinical heuristics and represents current medical practice. Overall, our results show the supremacy of SV and XG for both the prediction tasks although impacted by data characteristics, namely, the existence of missing values, complex data, and small-sized available inputs.

Discussion

With this study, we defined a predictive model approach capable to be well-understood by medical professionals, compared with the current practice, namely, the baseline approach (BL), and successfully showed the improvement achieved to the current medical knowledge.

Corneal confocal microscopy identifies corneal nerve loss and increased Langerhans cells in presymptomatic carriers and patients with hereditary transthyretin amyloidosis

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is a rare, but life-threatening protein misfolding disorder due to TTR gene mutations. Cardiomyopathy (ATTRv-CM) and polyneuropathy (ATTRv-PN) with early small nerve fibre involvement are the most common manifestations. Timely diagnosis and treatment initiation are key to limiting progression of disease. Corneal confocal microscopy (CCM) is a non-invasive method to quantify corneal small nerve fibres and immune cell infiltrates in vivo.

METHODS

This cross-sectional study investigated the utility of CCM in 20 patients with ATTRv amyloidosis (ATTRv-CM, n = 6; ATTRv-PN, n = 14) and presymptomatic carriers (n = 5) compared to 20 age- and sex-matched healthy controls. Corneal nerve fibre density, corneal nerve fibre length, corneal nerve branch density, and cell infiltrates were assessed.

RESULTS

Corneal nerve fibre density and nerve fibre length were significantly lower in patients with ATTRv amyloidosis compared to healthy controls regardless of the clinical phenotype (ATTRv-CM, ATTRv-PN) and corneal nerve fibre density was significantly lower in presymptomatic carriers. Immune cell infiltrates were only evident in patients with ATTRv amyloidosis, which correlated with reduced corneal nerve fibre density.

CONCLUSIONS

CCM identifies small nerve fibre damage in presymptomatic carriers and symptomatic patients with ATTRv amyloidosis and may serve as a predictive surrogate marker to identify individuals at risk of developing symptomatic amyloidosis. Furthermore, increased corneal cell infiltration suggests an immune-mediated mechanism in the pathogenesis of amyloid neuropathy.

Serum neurofilament light chain as a reliable biomarker of hereditary transthyretin-related amyloidosis-A Swiss reference center experience

Hereditary transthyretin-related (hATTR) amyloidosis is a rare disease, causing a disabling and life-threatening axonal length-dependent polyneuropathy. Monitoring of disease progression and treatment response is difficult. We aimed to determine if serum neurofilament light chain (sNfL) is a reliable and early biomarker of peripheral neuropathy in hATTR amyloidosis. We prospectively included 20 hATTR patients, 14 symptomatic and 6 asymptomatic. Patients were assessed at baseline and 1 year, including a full clinical examination with disease severity and functional scores, electrochemical skin conductance measurement with Sudoscan and nerve conduction studies, and sNfL level. hATTR patient sNfL were also compared with sNfL of 4532 healthy controls of a reference database by calculating age and BMI-adjusted Z scores. At baseline, median sNfL concentration was 3.6-fold higher in symptomatic than asymptomatic hATTR patients (P = .003), and this difference was also found in our under 60-years-old patients (P = .003). There was no significant difference of sNfL concentration between asymptomatic patients and healthy controls (Z-score of -0.29), but a significant difference between symptomatic patients and healthy controls (Z-score of 2.52). We found a significant correlation between sNfL levels and most clinical and electrophysiological disease severity scores, the strongest correlation being with the NIS score. sNfL seems to be a reliable biomarker of peripheral neuropathy severity in hATTR amyloidosis and can distinguish between asymptomatic and symptomatic patients. sNfL could also become a reliable biomarker to establish disease onset and treatment response.

Brazilian consensus for diagnosis, management and treatment of hereditary transthyretin amyloidosis with peripheral neuropathy: second edition

Hereditary transthyretin amyloidosis with peripheral neuropathy (ATTRv-PN) is an autosomal dominant inherited sensorimotor and autonomic polyneuropathy with over 130 pathogenic variants identified in the TTR gene. Hereditary transthyretin amyloidosis with peripheral neuropathy is a disabling, progressive and life-threatening genetic condition that leads to death in ∼ 10 years if untreated. The prospects for ATTRv-PN have changed in the last decades, as it has become a treatable neuropathy. In addition to liver transplantation, initiated in 1990, there are now at least 3 drugs approved in many countries, including Brazil, and many more are being developed. The first Brazilian consensus on ATTRv-PN was held in the city of Fortaleza, Brazil, in June 2017. Given the new advances in the area over the last 5 years, the Peripheral Neuropathy Scientific Department of the Brazilian Academy of Neurology organized a second edition of the consensus. Each panelist was responsible for reviewing the literature and updating a section of the previous paper. Thereafter, the 18 panelists got together virtually after careful review of the draft, discussed each section of the text, and reached a consensus for the final version of the manuscript.

Strategy for genetic analysis in hereditary neuropathy

Inherited neuropathies are a heterogeneous group of slowly progressive disorders affecting either motor, sensory, and/or autonomic nerves. Peripheral neuropathy may be the major component of a disease such as Charcot-Marie-Tooth disease or a feature of a more complex multisystemic disease involving the central nervous system and other organs. The goal of this review is to provide the clinical clues orientating the genetic diagnosis in a patient with inherited peripheral neuropathy. This review focuses on primary inherited neuropathies, amyloidosis, inherited metabolic diseases, while detailing clinical, neurophysiological and potential treatment of these diseases.

Current approaches to the diagnosis and management of amyloidosis

Amyloidosis is a collection of diseases caused by the misfolding of proteins that aggregate into insoluble amyloid fibrils and deposit in tissues. While these fibrils may aggregate to form insignificant localised deposits, they can also accumulate in multiple organs to the extent that amyloidosis can be an immediately life-threatening disease, requiring urgent treatment. Recent advances in diagnostic techniques and therapies are dramatically changing the disease landscape and patient prognosis. Delays in diagnosis and treatment remain the greatest challenge, necessitating physician awareness of the common clinical presentations that suggest amyloidosis. The most common types are transthyretin (ATTR) amyloidosis followed by immunoglobulin light-chain (AL) amyloidosis. While systemic AL amyloidosis was previously considered a death sentence with no effective therapies, significant improvement in patient survival has occurred over the past 2 decades, driven by greater understanding of the disease process, risk-adapted adoption of myeloma therapies such as proteosome inhibitors (bortezomib) and monoclonal antibodies (daratumumab) and improved supportive care. ATTR amyloidosis is an underdiagnosed cause of heart failure. Technetium scintigraphy has made noninvasive diagnosis much easier, and ATTR is now recognised as the most common type of amyloidosis because of the increased identification of age-related ATTR. There are emerging ATTR treatments that slow disease progression, decrease patient hospitalisations and improve patient quality of life and survival. This review aims to update physicians on recent developments in amyloidosis diagnosis and management and to provide a diagnostic and treatment framework to improve the management of patients with all forms of amyloidosis.

A natural history analysis of asymptomatic TTR gene carriers as they develop symptomatic transthyretin amyloidosis in the Transthyretin Amyloidosis Outcomes Survey (THAOS)

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) results from pathogenic mutations in the transthyretin (TTR) gene. This analysis aimed to better understand ATTRv amyloidosis development in asymptomatic TTR gene carriers.

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 TTR gene carriers. Asymptomatic TTR gene carriers were assessed longitudinally to identify those who developed ATTRv amyloidosis after enrolment in THAOS (data cut-off: 1 August 2021).

RESULTS

Of 740 asymptomatic TTR gene carriers, 268 (36.2%) (Val30Met, 212/613 [34.6%]; non-Val30Met, 48/111 [43.2%]) developed ATTRv amyloidosis within a median 2.2 years after enrolment. The most common first symptoms were sensory (49.5%) and autonomic (37.3%) neuropathy in Val30Met patients, and sensory neuropathy (45.8%) and cardiac disorder (22.9%) in non-Val30Met patients. Most patients first presented with a predominantly neurologic phenotype (Val30Met, 77.8%; non-Val30Met, 70.8%).

CONCLUSIONS

More than one-third of asymptomatic TTR gene carriers in THAOS developed ATTRv amyloidosis within a median 2 years of enrolment. Val30Met versus non-Val30Met patients had a lower transition rate. Given the importance of early treatment, these findings underscore the need for identification and careful monitoring of at-risk TTR gene carriers to enable prompt treatment.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00628745.

[National survey of presymptomatic genetic testing for adult-onset hereditary neuromuscular diseases-system development for after the establishment of therapies]

As therapies for hereditary neuromuscular diseases are developed, the need for presymptomatic genetic testing and genetic counseling for early treatment is expected to increase. In Japan, there is no uniformly recommended protocol for presymptomatic genetic testing. In order to provide basic data for the establishment of a presymptomatic genetic testing system, we surveyed medical genetics departments in Japan about their current status (response rate: 67.4%). The questionnaire survey revealed that approximately 60% of facilities had established their own procedures for presymptomatic genetic testing, but the approaches used varied from facility to facility. The interview survey enabled us to identify the essential factors for the establishment of a presymptomatic genetic testing system for each case, each facility, and at the overall level. In the future, there is a need to develop a standardized protocol to help establish a presymptomatic genetic testing system.

Clinical and Genetic Evaluation of People with or at Risk of Hereditary ATTR Amyloidosis: An Expert Opinion and Consensus on Best Practice in Ireland and the UK

Hereditary transthyretin-mediated amyloidosis (hATTR) is challenging to diagnose early owing to the heterogeneity of clinical presentation, which differs according to the TTR gene variant and its penetrance in each individual. The TTR variants seen most frequently in the UK and Ireland (T80A, V142I and V50M) differ to those commonly occurring in other geographic locations and warrant a specific consideration for diagnosis and genetic testing. In addition, recent availability of treatment for this condition has reinforced the need for a more consistent approach to the management of patients, including access to specialist services, genetic testing and counselling, and clinical investigation for families living in the UK and Ireland. A multidisciplinary panel of experts from the UK and Ireland was convened to identify the current challenges, provide recommendations, and develop a consensus for the diagnosis and screening of people with, or at risk of, hATTR. Over a series of meetings, experts shared their current practices and drafted, refined and approved a consensus statement. This consensus statement provides recommendations for three different groups: (1) people with symptoms raising a possibility of hATTR amyloidosis; (2) people with biopsy-confirmed hATTR amyloidosis; and (3) people without symptoms who may have hATTR amyloidosis (i.e. relatives of people with identified TTR variants). For each group, recommendations are made for the required steps for the diagnosis and follow-up of symptomatic patients, and for guidance on the specialist support for counselling and pre-symptomatic genetic testing of at-risk individuals. This guidance is intended to be practical and based on available evidence. The aim is for regional amyloid specialist centres to provide timely diagnosis, clinical screening, and treatment for individuals and their families with hATTR amyloidosis.

Practical guidelines for the diagnosis and treatment of transthyretin amyloid cardiomyopathy (ATTR-CM or transthyretin cardiac amyloidosis)

This paper summarizes the data from updated international protocols and guidelines for diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM). The invasive and non-invasive diagnosis techniques and their combinations are briefly reviewed; the evidentiary foundations for each diagnostic option and tool are analyzed. The paper describes a customized algorithm for sequential diagnosis and differential diagnosis of patients with suspected ATTR-CM with allowance for the combination of clinical signs and diagnostic findings. Along with the awareness of primary care providers about the red flags of the disease and visualization criteria, as well as providing information to the patients about the possibility of performing therapy of ATTR amyloidosis and the risks of delayed diagnosis, the proposed algorithm enables timely patient routing and prescribing specific treatment.

Hereditary transthyretin amyloidosis overview

Hereditary amyloidogenic transthyretin (ATTRv) amyloidosis is a rare autosomal dominantly inherited disorder caused by mutations in the transthyretin (TTR) gene. The pathogenetic model of ATTRv amyloidosis indicates that amyloidogenic, usually missense, mutations destabilize the native TTR favouring the dissociation of the tetramer into partially unfolded species that self-assemble into amyloid fibrils. Amyloid deposits and monomer-oligomer toxicity are the basis of multisystemic ATTRv clinical involvement. Peripheral nervous system (autonomic and somatic) and heart are the most affected sites. In the last decades, a better knowledge of pathomechanisms underlying the disease led to develop novel and promising drugs that are rapidly changing the natural history of ATTRv amyloidosis. Thus, clinicians face the challenge of timely diagnosis for addressing patients to appropriate treatment. As well, the progressive nature of ATTRv raises the issue of presymptomatic testing and risk management of carriers. The main aim of this review was to focus on what we know about ATTRv so far, from pathogenesis to clinical manifestations, diagnosis and hence patient's monitoring and treatment, and from presymptomatic testing to management of carriers.

The functional and structural evaluation of small fibers in asymptomatic carriers of p.Val50Met (Val30Met) mutation

Therapeutic advances in hereditary amyloid transthyretin (ATTRv) amyloidosis with polyneuropathy extended life expectancy and delayed symptom progression especially in patients with early disease. Thus, detection and monitoring of asymptomatic carriers gained importance. However, there is still limited consensus on genetic screening of ATTRv-PN patients' family members and diagnostic tests that must be done in the follow-up. In this study, we followed prospectively five asymptomatic carriers of a family with ATTRV30M (p.Val50Met) mutation by different diagnostic tests for three years. The carriers were followed by neurological examination, nerve conduction studies, sympathetic skin response test, heart rate variability, SFN-SIQ and DN4 questionnaires, quantitative sensory testing (QST), skin biopsy and in vivo corneal confocal microscopy. Nerve conduction studies, sympathetic skin response test and heart rate variability were normal in all for three years. Baseline QST and SFN-SIQ were normal but became abnormal during follow-up of two individuals who developed small fiber neuropathy symptoms. Baseline intraepidermal nerve fiber density was low in three carriers and decreased to below normative values in all during follow-up, while corneal sub-basal nerve density was low in all carriers compared to controls during the entire follow-up. Thus, our study showed that SFN-SIQ and QST are useful diagnostic tools to detect the transition to symptomatic ATTRv-polyneuropathy.

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.

Current and Emerging Therapies for Hereditary Transthyretin Amyloidosis: Strides Towards a Brighter Future

The past few years have witnessed an unprecedented acceleration in the clinical development of novel therapeutic options for hereditary transthyretin amyloidosis. Recently approved agents and drugs currently under investigation not only represent a major breakthrough in this field but also provide validation of the therapeutic potential of innovative approaches, like RNA interference and CRISPR-Cas9-mediated gene editing, in rare inherited disorders. In this review, we describe the evolving therapeutic landscape for hereditary transthyretin amyloidosis and discuss how this highly disabling and fatal condition is turning into a treatable disease. We also provide an overview of the molecular mechanisms involved in transthyretin (TTR) amyloid formation and regression, to highlight how a deeper understanding of these processes has contributed to the identification of novel treatment targets. Finally, we focus on major areas of uncertainty and unmet needs that deserve further efforts to improve long-term patients' outcomes and allow for a brighter future.

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.

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.

Clinical approach to genetic testing in amyloid cardiomyopathy: from mechanism to effective therapies

PURPOSE OF REVIEW

To highlight the evolving understanding of genetic variants, utility of genetic testing, and the selection of novel therapies for cardiac amyloidosis.

RECENT FINDINGS

The last decade has seen considerable progress in cardiac amyloidosis recognition given the advancement in cardiac imaging techniques and widespread availability of genetic testing. A significant shift in the understanding of a genetic basis for amyloidosis has led to the development of disease-modifying therapeutic strategies that improve survival.

SUMMARY

The systemic amyloidoses are disorders caused by extracellular deposition of misfolded amyloid fibrils in various organs. Immunoglobulin light-chain or transthyretin amyloidosis are the most common types associated with cardiac manifestations. Genetic testing plays a central role in the identification of genotypes that are associated with different clinical phenotypes and influence prognosis. Given the emergence of effective therapies, a systematic approach to the diagnosis of cardiac amyloidosis, with the elucidation of genotype when indicated, is essential to select the appropriate treatment.

Recommendations for pre-symptomatic genetic testing for hereditary transthyretin amyloidosis in the era of effective therapy: a multicenter Italian consensus

Hereditary transthyretin amyloidosis (ATTRv, v for variant) is a late-onset, autosomal dominant disease caused by progressive extracellular deposition of transthyretin amyloid fibrils, leading to organ damage and death. For other late-onset fatal diseases, as Huntington’s disease, protocols for pre-symptomatic genetic testing (PST) are available since decades. For ATTRv, limited experience has been reported to date, mostly gathered before the availability of approved therapies. We aimed at developing recommendations for a safe and feasible PST protocol in ATTRv in the era of emerging treatments, taking also into account Italian patients’ characteristics and healthcare system rules. After an initial survey on ongoing approaches to PST for ATTRv in Italy, two roundtable meetings were attended by 24 experts from 16 Italian centers involved in the diagnosis and care of this disease. Minimal requirements for PST offer and potential critical issues were highlighted. By November 2019, 457 families affected by ATTRv with 209 molecularly confirmed pre-symptomatic carriers were counted. The median age at PST was 41.3 years of age, regardless of the specific mutation. Half of the Italian centers had a multidisciplinary team, including a neurologist, an internist, a cardiologist, a medical geneticist and a psychologist, although in most cases not all the specialists were available in the same center. A variable number of visits was performed at each site. Experts agreed that PST should be offered only in the context of genetic counselling to at risk individuals aged 18 or older. Advertised commercial options for DNA testing should be avoided. The protocol should consist of several steps, including a preliminary clinical examination, a pre-test information session, an interval time, the genetic test and a post-test session with the disclosure of the test results, in the context of an experienced multidisciplinary team. Recommendations for best timing were also defined. Protocols for PST in the context of ATTRv can be refined to offer at risk individuals the best chance for early diagnosis and timely treatment start, while respecting autonomous decisions and promoting safe psychological adjustment to the genetic result.

Diagnosis and treatment of cardiac amyloidosis: an interdisciplinary consensus statement

The prevalence and significance of cardiac amyloidosis have been considerably underestimated in the past; however, the number of patients diagnosed with cardiac amyloidosis has increased significantly recently due to growing awareness of the disease, improved diagnostic capabilities and demographic trends. Specific therapies that improve patient prognosis have become available for certain types of cardiac amyloidosis. Thus, the earliest possible referral of patients with suspicion of cardiac amyloidosis to an experienced center is crucial to ensure rapid diagnosis, early initiation of treatment, and structured patient care. This requires intensive collaboration across several disciplines, and between resident physicians and specialized centers. The aim of this consensus statement is to provide guidance for the rapid and efficient diagnosis and treatment of light-chain amyloidosis and transthyretin amyloidosis, which are the most common forms of cardiac amyloidosis.

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.

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.

Avoiding misdiagnosis: expert consensus recommendations for the suspicion and diagnosis of transthyretin amyloidosis for the general practitioner

BACKGROUND

Transthyretin amyloidosis (also known as ATTR amyloidosis) is a systemic, life-threatening disease characterized by transthyretin (TTR) fibril deposition in organs and tissue. A definitive diagnosis of ATTR amyloidosis is often a challenge, in large part because of its heterogeneous presentation. Although ATTR amyloidosis was previously considered untreatable, disease-modifying therapies for the treatment of this disease have recently become available. This article aims to raise awareness of the initial symptoms of ATTR amyloidosis among general practitioners to facilitate identification of a patient with suspicious signs and symptoms.

METHODS

These consensus recommendations for the suspicion and diagnosis of ATTR amyloidosis were developed through a series of development and review cycles by an international working group comprising key amyloidosis specialists. This working group met to discuss the barriers to early and accurate diagnosis of ATTR amyloidosis and develop a consensus recommendation through a thorough search of the literature performed using PubMed Central.

RESULTS

The cardiac and peripheral nervous systems are most frequently involved in ATTR amyloidosis; however, many patients often also experience gastrointestinal and other systemic manifestations. Given the multisystemic nature of symptoms, ATTR amyloidosis is often misdiagnosed as a more common disorder, leading to significant delays in the initiation of treatment. Although histologic evaluation has been the gold standard to confirm ATTR amyloidosis, a range of tools are available that can facilitate early and accurate diagnosis. Of importance, genetic testing should be considered early in the evaluation of a patient with unexplained peripheral neuropathy.

CONCLUSIONS

A diagnostic algorithm based on initial red flag symptoms and manifestations of cardiac or neurologic involvement will facilitate identification by the general practitioner of a patient with clinically suspicious symptoms, enabling subsequent referral of the patient to a multidisciplinary specialized medical center.

Impact of Genetic Testing in Transthyretin (ATTR) Cardiac Amyloidosis

PURPOSE OF REVIEW

The review's main focus centers on the genetics of hereditary cardiac amyloidosis, highlighting the opportunities and challenges posed by the widespread availability of genetic screening and diagnostic cardiac imaging.

RECENT FINDINGS

Advancements in cardiac imaging, heightened awareness of the ATTR amyloidosis diagnosis, and greater access to genetic testing have all led to an increased appreciation of the prevalence of ATTR cardiac amyloidosis. Elucidation of the TTR molecular structure and effect of mutations on TTR function have allowed for novel TTR therapy development leading to clinical implementation of transthyretin stabilizers and transthyretin gene silencers. The transthyretin amyloidoses are a diverse group of protein misfolding disorders with cardiac and peripheral/autonomic nervous system manifestations due to protein deposition. Genetic screening allows for the early identification of asymptomatic TTR mutation carriers. With the advent of TTR-specific therapeutics, clinical guidance is necessary for the management of individuals with mutations in the TTR gene without evidence of disease.

Systemic Amyloidosis Recognition, Prognosis, and Therapy: A Systematic Review

IMPORTANCE

Many patients with systemic amyloidosis are underdiagnosed. Overall, 25% of patients with immunoglobulin light chain (AL) amyloidosis die within 6 months of diagnosis and 25% of patients with amyloid transthyretin (ATTR) amyloidosis die within 24 months of diagnosis. Effective therapy exists but is ineffective if end-organ damage is severe.

OBJECTIVE

To provide evidence-based recommendations that could allow clinicians to diagnose this rare set of diseases earlier and enable accurate staging and counseling about prognosis.

EVIDENCE REVIEW

A comprehensive literature search was conducted by a reference librarian with publication dates from January 1, 2000, to December 31, 2019. Key search terms included amyloid, amyloidosis, nephrotic syndrome, heart failure preserved ejection fraction, and peripheral neuropathy. Exclusion criteria included case reports, non-English-language text, and case series of fewer than 10 patients. The authors independently selected and appraised relevant literature.

FINDINGS

There was a total of 1769 studies in the final data set. Eighty-one articles were included in this review, of which 12 were randomized clinical trials of therapy that included 3074 patients, 9 were case series, and 3 were cohort studies. The incidence of AL amyloidosis is approximately 12 cases per million persons per year and there is an estimated prevalence of 30 000 to 45 000 cases in the US and European Union. The incidence of variant ATTR amyloidosis is estimated to be 0.3 cases per year per million persons with a prevalence estimate of 5.2 cases per million persons. Wild-type ATTR is estimated to have a prevalence of 155 to 191 cases per million persons. Amyloidosis should be considered in the differential diagnosis of adult nondiabetic nephrotic syndrome; heart failure with preserved ejection fraction, particularly if restrictive features are present; unexplained hepatomegaly without imaging abnormalities; peripheral neuropathy with distal sensory symptoms, such as numbness, paresthesia, and dysesthesias (although the autonomic manifestations occasionally may be the presenting feature); and monoclonal gammopathy of undetermined significance with atypical clinical features. Staging can be performed using blood testing only. Therapeutic decision-making for AL amyloidosis involves choosing between high-dose chemotherapy and stem cell transplant or bortezomib-based chemotherapy. There are 3 therapies approved by the US Food and Drug Administration for managing ATTR amyloidosis, depending on clinical phenotype.

CONCLUSIONS AND RELEVANCE

All forms of amyloidosis are underdiagnosed. All forms now have approved therapies that have been demonstrated to improve either survival or disability and quality of life. The diagnosis should be considered in patients that have a multisystem disorder involving the heart, kidney, liver, or nervous system.

Circulating microRNAs Profile in Patients With Transthyretin Variant Amyloidosis

Transthyretin variant amyloidosis (ATTRv) is a rare autosomal dominant disease characterized by the accumulation of amyloid in many organs, mostly causing a sensory-motor neuropathy, cardiomyopathy, and dysautonomia. The aim of the study was to report microRNAs (miRNAs) expression profile identified in the blood of ATTRv patients. Ten ATTRv patients, 10 asymptomatic carriers of transthyretin variant (TTRv), 10 patients with Charcot-Marie-Tooth (CMT) disease, and 10 healthy controls were studied. Human Schwann cells cultures were used to study the regulatory effects of miR-150-5p on the expression of cAMP response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF). ATTRv patients had 33 miRNAs up-regulated and 48 down-regulated versus healthy controls; 9 miRNAs were up-regulated and 30 down-regulated versus CMT patients; 19 miRNAs were up-regulated and 38 down-regulated versus asymptomatic TTRv carriers. Twelve out of the 19 upregulated miRNAs had a fold increase higher than 100. The validation experiment indicated miR-150-5p as a valuable biomarker to differentiate ATTRv patients from asymptomatic TTRv carriers (AUC: 0.9728; p < 0.0001). Schwann cells culture model demonstrated that miR-150-5p is a powerful negative regulator of CREB, BDNF, and NGF genes. Identification of deregulated miRNAs can help in understanding the complex pathomechamism underlying the development of ATTRv and related multisystemic pathology. Further investigations are needed on the role of circulating miR-150-5p to predict the shift of TTRv carriers from an asymptomatic status to symptoms appearance.

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.

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 (ATTR_v) 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 ATTR_v 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 ATTR_v 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.

Monitoring of asymptomatic family members at risk of hereditary transthyretin amyloidosis for early intervention with disease-modifying therapies

BACKGROUND

Hereditary transthyretin (ATTRv) amyloidosis is an adult-onset, systemic disorder caused by mutations in the transthyretin (TTR) gene. As ATTRv amyloidosis is inherited in an autosomal dominant manner, family members of the patients are at risk of developing the disease.

METHODS

With an objective of discussing recommendations on monitoring of family members for early diagnosis of ATTRv amyloidosis, we held a medical advisory board meeting in Tokyo, Japan, in October 2017.

RESULTS

Our recommendations are summarized as follows: periodic follow-up genetic counseling should be offered to asymptomatic gene mutation carriers; follow-up assessments should be started when the carriers are still asymptomatic to test for amyloidosis onset, irrespective of TTR genotype and age at onset in the particular family. We suggest annual routine assessments and in-depth assessments every 3-5 years, with the frequency of these increased as required. Periodical monitoring of asymptomatic gene mutation carriers is crucial for attending physicians to detect early signs or symptoms of the disease and start disease-modifying therapy (DMT).

CONCLUSIONS

The monitoring strategy for asymptomatic TTR gene mutation carriers should progress toward rapid diagnosis and early intervention with DMT. This approach may be more appropriate for countries with more resources.

miRNA-31 Improves Cognition and Abolishes Amyloid-β Pathology by Targeting APP and BACE1 in an Animal Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia worldwide, characterized by progressive memory impairment, behavioral changes, and, ultimately, loss of consciousness and death. Recently, microRNA (miRNA) dysfunction has been associated with increased production and impaired clearance of amyloid-β (Aβ) peptides, whose accumulation is one of the most well-known pathophysiological markers of this disease. In this study, we identified several miRNAs capable of targeting key proteins of the amyloidogenic pathway. The expression of one of these miRNAs, miR-31, previously found to be decreased in AD patients, was able to simultaneously reduce the levels of APP and Bace1 mRNA in the hippocampus of 17-month-old AD triple-transgenic (3xTg-AD) female mice, leading to a significant improvement of memory deficits and a reduction in anxiety and cognitive inflexibility. In addition, lentiviral-mediated miR-31 expression significantly ameliorated AD neuropathology in this model, drastically reducing Aβ deposition in both the hippocampus and subiculum. Furthermore, the increase of miR-31 levels was enough to reduce the accumulation of glutamate vesicles in the hippocampus to levels found in non-transgenic age-matched animals. Overall, our results suggest that miR-31-mediated modulation of APP and BACE1 can become a therapeutic option in the treatment of AD.

Diagnosis and Treatment of Hereditary Transthyretin Amyloidosis (hATTR) Polyneuropathy: Current Perspectives on Improving Patient Care

Hereditary transthyretin amyloidosis (hATTR) with polyneuropathy (formerly known as Familial Amyloid Polyneuropathy) is a rare disease due to mutations in the gene encoding transthyretin (TTR) and characterized by multisystem extracellular deposition of amyloid, leading to dysfunction of different organs and tissues. hATTR amyloidosis represents a diagnostic challenge for neurologists considering the great variability in clinical presentation and multiorgan involvement. Generally, patients present with polyneuropathy, but clinicians should consider the frequent cardiac, ocular and renal impairment. Especially a hypertrophic cardiomyopathy, even if usually latent, is identifiable in at least 50% of the patients. Therapeutically, current available options act at different stages of TTR production, including synthesis inhibition (liver transplantation and/or gene-silencing drugs) or tetramer TTR stabilization (TTR stabilizers), increasing survival at different disease stages.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/n8sg_YlGJiA

Expert consensus recommendations to improve diagnosis of ATTR amyloidosis with polyneuropathy

Amyloid transthyretin (ATTR) amyloidosis with polyneuropathy (PN) is a progressive, debilitating, systemic disease wherein transthyretin protein misfolds to form amyloid, which is deposited in the endoneurium. ATTR amyloidosis with PN is the most serious hereditary polyneuropathy of adult onset. It arises from a hereditary mutation in the TTR gene and may involve the heart as well as other organs. It is critical to identify and diagnose the disease earlier because treatments are available to help slow the progression of neuropathy. Early diagnosis is complicated, however, because presentation may vary and family history is not always known. Symptoms may be mistakenly attributed to other diseases such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), idiopathic axonal polyneuropathy, lumbar spinal stenosis, and, more rarely, diabetic neuropathy and AL amyloidosis. In endemic countries (e.g., Portugal, Japan, Sweden, Brazil), ATTR amyloidosis with PN should be suspected in any patient who has length-dependent small-fiber PN with autonomic dysfunction and a family history of ATTR amyloidosis, unexplained weight loss, heart rhythm disorders, vitreous opacities, or renal abnormalities. In nonendemic countries, the disease may present as idiopathic rapidly progressive sensory motor axonal neuropathy or atypical CIDP with any of the above symptoms or with bilateral carpal tunnel syndrome, gait disorders, or cardiac hypertrophy. Diagnosis should include DNA testing, biopsy, and amyloid typing. Patients should be followed up every 6–12 months, depending on the severity of the disease and response to therapy. This review outlines detailed recommendations to improve the diagnosis of ATTR amyloidosis with PN.