Genetic epidemiology of familial amyloidotic polyneuropathy (FAP)-type I in Póvoa do Varzim and Vila do Conde (north of Portugal)

Altered connectivity of central autonomic network: effects of dysautonomia in hereditary transthyretin amyloidosis with polyneuropathy

BACKGROUND

Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) is a progressive fatal disorder caused by deposition of mutant transthyretin (TTR) amyloids mainly in the nerves and heart. Autonomic dysfunction is a major disabling manifestation, affecting 90% of patients with late-onset ATTRv-PN. The current study aimed to investigate brain functional alterations associated with dysautonomia due to peripheral autonomic nerve degeneration in ATTRv-PN.

METHODS

Resting-state functional MRI data were acquired from 43 ATTRv-PN patients predominantly of A97S (p.A117S) genotype, and the functional connectivity of central autonomic regions was assessed.

RESULTS

Compared with age-matched healthy controls, the ATTRv-PN patients exhibited (1) reduced functional connectivity of the central autonomic regions such as hypothalamus, amygdala, anterior insula, and middle cingulate cortex with brain areas of the limbic, frontal, and somatosensory systems, and (2) correlations of reduced functional autonomic connectivity with the severity of autonomic dysfunction especially orthostatic intolerance, decreased heart rate variability, and greater clinical disability.

CONCLUSIONS

Our findings provide evidence linking peripheral autonomic dysfunction with altered connectivity in the central autonomic network in ATTRv-PN.

PARS PLANA VITRECTOMY FOR THE TREATMENT OF VITREOUS AMYLOID IN PATIENTS WITH HEREDITARY TRANSTHYRETIN AMYLOIDOSIS

PURPOSE

To describe a series of patients with hereditary transthyretin amyloidosis with vitreous amyloid and to study the efficacy and safety of pars plana vitrectomy for its treatment.

METHODS

Retrospective study of 266 patients with hereditary transthyretin amyloidosis because of Val30Met mutation submitted to pars plana vitrectomy for vitreous amyloid, with a minimum of 3-month follow-up. Indications for surgery were disabling myodesopsia or two lines loss in visual acuity. Only the first operated eye was considered for analysis.

RESULTS

Male patients were operated at younger age (51.0 vs. 53.6, P < 0.001). Best-corrected visual acuity improved from 0.38 to 0.89 (decimal scale, P < 0.001). Preoperative glaucoma was associated with lower gain in visual acuity ( P < 0.001). During the follow-up, 69%, 22%, and 1% developed new-onset glaucoma, retinal angiopathy, or retinal detachment, respectively, and 36% required cataract surgery. Pars plana vitrectomy was also required in the fellow eye in 57%. Hereditary transthyretin amyloidosis-related death occurred in 27%, 9.3 (95% confidence interval 8.0 to 10.7) years after pars plana vitrectomy.

CONCLUSION

Vitreous opacities are frequently the first symptomatic manifestation of ocular amyloidosis. Moreover, they may be a marker of mortality. Vitrectomy is a safe and effective treatment, but these patients require long-term follow-up to monitor the development or worsening of glaucoma or retinal angiopathy.

Modified ex-PRESS technique versus Ahmed glaucoma valve as primary glaucoma surgery for hereditary transthyretin amyloidosis glaucoma

BACKGROUND

To compare the efficacy of modified Ex-PRESS technique (ExP) versus Ahmed Glaucoma Valve (AGV) as primary surgery in hereditary transthyretin amyloidosis (ATTRv) secondary glaucoma.

METHODS

Retrospective study at the national amyloidosis centre. Success was defined as an IOP ≥ 6 mmHg and ≤ 21 mmHg with no need for further glaucoma surgery or laser trabeculoplasty and without loss of light perception at the time of the last follow-up. Secondary outcomes included surgical complications, need for hypotensive drugs, and endothelial cell loss. Patients submitted to previous glaucoma surgery were excluded.

RESULTS

We included 180 eyes of 150 patients, 121 in AGV and 59 in ExP group. No significant baseline differences were found between groups. At the time of last follow-up, both groups exhibited significant intraocular pressure (IOP) reduction (p < .001) and number of glaucoma medications (p < .001). Kaplan-Meyer analysis showed higher cumulative probability of success for AGV group (80.1% vs. 41.1%, p < .001) and higher mean time to failure (54.5 vs. 36.9 months, respectively, p < 0.001) at 60 months follow-up. AGV showed lower hazard (HR 0.21, 95% CI [0.111-0.407], p < .001) for failure.

CONCLUSION

AGV and ExP are safe and effective techniques in the treatment of ATTRv secondary glaucoma. However, AGV's efficacy seems to be more durable.

The Physical Driving Forces of Conformational Transition for TTR91-96 with Proline Mutations

Pathological aggregation of essentially dissociated Transthyretin (TTR) monomer proteins, driven by misfolding and self-interaction, is associated with Transthyretin amyloidosis (ATTR) disease. The TTR monomer proteins consist of several fragments that tend to self-aggregate. Recent experimental studies showed that the sequence of residues TTR91-96 plays an important role in self-aggregation. However, the mechanisms underlying the misfolding and aggregation of the TTR91-96 monomers are still unknown. In this study, we used microsecond molecular dynamics simulations to investigate the misfolding and self-assembly of TTR91-96 Octamers. We also investigated E92P and V94P mutants for comparative analysis. The analysis indicates that hydrophobic interactions and π-π stacking patterns play important roles in reducing the β-sheet content in the V94P and E92P mutants. Additionally, our findings reveal the conformational transition of TTR91-96 octamer from closed β-barrel, open β-barrel to the β-bilayer aggregation. We further elucidate the dynamic mechanism of the transition from intermediate states to stable states. Overall, our research may contribute to the development of drug design to combat fibrous amyloid fibrous diseases.

Hereditary transthyretin amyloidosis: a myriad of factors that influence phenotypic variability

Hereditary transthyretin-related amyloidosis (ATTRv amyloidosis) is a rare and progressively debilitating disease characterized by the deposition of transthyretin (TTR) amyloid fibrils in various organs and tissues, most commonly in the heart and peripheral nerves. This pathological deposition can lead to significant organ dysfunction and, ultimately, organ failure. ATTRv amyloidosis exhibits a broad range of clinical presentations, from purely neurological symptoms to purely cardiac manifestations, as well as mixed phenotypes which result from both neurological and cardiac implications. This wide phenotypical spectrum realistically challenges disease diagnosis and prognosis, especially in individuals without or with an unknown family history. Multiple factors are thought to contribute to this variability, including genetic, epigenetic, and even environmental influences. Understanding these factors is crucial, as they can significantly affect disease expression and progression. This review aims to summarize each of these contributing factors, to help elucidate the current knowledge on the phenotypical variability of ATTRv amyloidosis.

Cardiac Amyloidosis: How Its Epidemiology is Changing

Cardiac amyloidosis (CA) encompasses a group of disorders characterized by an abnormal accumulation of amyloid fibrils in the heart, leading to impaired cardiac function and ultimately heart failure. While the incidence of immunoglobulin light chains amyloidosis incidence seems stable at 8 to 15.2 cases per million persons (PMP)/year, the incidence and prevalence of wild type transthyretin-CA are steadily increasing, being currently estimated at 14 to 27 cases PMP/year and 30 to 170 cases PMP, respectively. This review explores the dynamic landscape of CA epidemiology and its implications for screening and management strategies.

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.

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.

Pathological spectrum of hereditary transthyretin renal amyloidosis and clinicopathologic correlation: a French observational study

BACKGROUND

Cardiac and neurological involvements are the main clinical features of hereditary transthyretin (ATTRv) amyloidosis. Few data are available about ATTRv amyloid nephropathy (ATTRvN).

METHODS

We retrospectively included 30 patients with biopsy-proven ATTRvN [V30M (26/30) including two domino liver recipients, S77Y (2/30), V122I (1/30) and S50R (1/30) variants] from two French reference centers. We described the pathological features by comparing amyloid deposits distribution to patients with AL or AA amyloidosis, and sought to determine clinicopathological correlation with known disease-modifying factors such as TTR variant, gender and age at diagnosis.

RESULTS

In comparison with AL and AA amyloidosis, ATTRv patients had similar glomerular, arteriolar and arterial amyloid deposits, but more cortical and medullary tubulointerstitial (33%, 44%, 77%, P = .03) involvement. While the presence of glomerular deposits is associated with the range of proteinuria, some patients with abundant glomerular ATTRv amyloidosis had no significant proteinuria. V30M patients had more glomerular (100% and 25%, odds ratio = 114, 95% confidence interval 3.85-3395.00, P = .001) deposits, and higher estimated glomerular filtration rate [50 (interquartile range 44-82) and 27 (interquartile range 6-31) mL/min/1.73 m², P = .004] than non-V30M patients. We did not find difference in amyloid deposition according to gender or age at diagnosis.

CONCLUSION

ATTRvN affects all kidney compartments, but compared with AL/AA amyloidosis, ATTRvN seems to involve more frequently tubulointerstitial areas. V30M patients represents the dominant face of the disease with a higher risk of glomerular/arteriolar involvement. ATTRvN should thus be considered in patients, and potential relatives, with ATTRv amyloidosis and kidney dysfunction, regardless of proteinuria level.

Disease risk estimates in V30M variant transthyretin amyloidosis (A-ATTRv) from Mallorca

BACKGROUND

Variant transthyretin amyloidosis (A-ATTRv) is an autosomal dominant disease caused by a range of TTR gene variants which entail great phenotypical heterogeneity and penetrance. In Majorca, the A-ATTRv caused by the V30M gene variant (A-ATTRV30M) is the most common. Since asymptomatic carriers are at risk of developing the disease, estimating age of onset is vital for proper management and follow-up. Thus, the aim of this study was to estimate age-related penetrance in ATTRV30M variant carriers from Majorca.

METHODS

The disease risk among carriers from ATTRV30M families from Majorca was estimated by Non-parametric survival estimation. Factors potentially involved in the disease expression, namely gender and parent of origin were also analysed.

RESULTS

A total of 48 heterozygous ATTRV30M families (147 affected patients and 123 were asymptomatic carriers) were included in the analysis. Penetrance progressively increased from 6% at 30 years to 75% at 90 years of age. In contrast to other European populations, we observe a similar risk for both males and females, and no difference of risk according to the parent of origin.

CONCLUSIONS

In this first study assessing the age-related penetrance of ATTRV30M variant in Majorcan families, no effect of gender or parent of origin was observed. These findings will be helpful for improving management and follow-up of TTR variant carrier individuals.

Study of the parent-of-origin effect in monogenic diseases with variable age of onset. Application on ATTRv

In genetic diseases with variable age of onset, an accurate estimation of the survival function for the mutation carriers and also modifying factors effects estimations are important for the management of asymptomatic gene carriers across life. Among the modifying factors, the gender of the parent transmitting the mutation (i.e. the parent-of-origin effect) has been shown to have a significant effect on survival curve estimation on transthyretin familial amyloid polyneuropathy (ATTRv) families. However, as most genotypes are unknown, the parent-of-origin must be calculated through a probability estimated from the pedigree. We propose in this article to extend the method providing mutation carrier survival estimates in order to estimate the parent-of-origin effect. The method is both validated on simulated data and applied to familly samples with ATTRv.

Transthyretin Variant Amyloidosis with a TTR A97D (p.A117D) Mutation Manifesting Remarkable Asymmetric Neuropathy

We herein report a 68-year-old Japanese man with sporadic variant transthyretin (ATTRv) amyloidosis harboring the novel variant A97D (p.A117D) in TTR. He had slow development of asymmetric neuropathy, unintentional weight loss, mild autonomic failure and mild cardiomyopathy. TTR amyloid deposition on the gastric duodenal mucosa was detected. In silico analyses predicted that TTR A97D (p.A117D) altered the structure and function of the TTR protein. ATTRv amyloidosis is often difficult to diagnose in non-endemic regions due to its diverse phenotypes, such as atypical peripheral nerve involvement and a rare family history.

Natural course and determinants of short-term kidney function decline in hereditary transthyretin amyloidosis: a French observational study

Data regarding renal involvement in patients with hereditary transthyretin (ATTRv) amyloidosis are scarce and the natural course of chronic kidney disease (CKD) in this population remains unclear. This observational study, including adult patients diagnosed with ATTRv amyloidosis at the French Reference Centre for Cardiac Amyloidosis, investigated renal function outcome and its determinants. Multivariable logistic regression models identified factors associated with CKD at baseline. Determinants of the change in estimated glomerular filtration rate (eGFR) over 24 months of follow-up were assessed with a multivariable linear mixed-effects model. In total, 232 patients (78 women [34%], mean age: 64 years) with ATTRv amyloidosis were classified on the basis of their TTR variants: ATTRV122I (37%), ATTRV30M (29%), and other variants (34%). Median baseline eGFR was 78 ml/min/1.73 m². Seventy-two patients (31%) had an eGFR below 60 ml/min/1.73m² and 27/137 patients (20%) had significant proteinuria (urine protein/creatinine ratio ≥30 mg/mmol). Renal biopsy, performed in four cases, found typical Congo red-positive and TTR-labelled amyloid deposits in all cases. Older age (OR 1.07, p < .001) and a prior history of hypertension (OR 2.09, p = .04) were associated with a higher prevalence of CKD at baseline, whereas higher left ventricular global longitudinal strain (LVGLS) (OR 0.83, p < .001) was associated with a lower prevalence. The estimated change in eGFR was -7.12 [-9.61, -4.63] and -8.21 [-10.81, -5.60] ml/min/1.73 m² after 12 and 24 months of follow-up, respectively. eGFR decline was independently associated with older age ((67-74], coefficient= -14.35 mL/min/1.73 m², p < .01, >74, coefficient = -22.93 mL/min/1.73 m², p < .001, versus <56), ATTRV122I (coefficient = -17.17 mL/min/1.73m², p < .01, versus ATTRV30M) and LVGLS (coefficient = 1.22, p < .01). These data suggest that CKD is a common finding in patients with ATTRv amyloidosis, and that eGFR decline is rapid during the first year of evaluation. Older age, lower LVGLS and ATTRV122I were associated with a worse renal outcome. Further studies are now needed to evaluate effects of new targeted therapies on long term renal function.

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.

Prevalence estimation of ATTRv in China based on genetic databases

Introduction: Amyloid transthyretin (ATTR) is divided into either hereditary (ATTRv) or sporadic (ATTRwt) and ATTRv is a rare hereditary disease transmitted as an autosomal dominant manner. Its global prevalence is traditionally estimated as 5,000 to 10,000 persons. However, it may be underestimated and the exact prevalence of ATTRv in China mainland remains unknown. Methods: The Genome Aggregation database (gnomAD) database (containing 125,748 exomes) and two genomic sequencing databases--China Metabolic Analytics Project (ChinaMAP) (containing 10588 individuals) and Amcarelab gene database (containing 45392 exomes), were integrated to estimate the prevalence of ATTRv in the world and mainland Chinese populations. Pathogenic variants allele frequency and the prevalence of ATTRv was calculated. Results: Six variants, counting 470 alleles, were defined as pathogenic variants in gnomAD. The prevalence of ATTRv in the world population was 57.4/100,000. Two variants (2 allele counts) and 15 variants (34 individuals) were defined as pathogenic variants in the ChinaMAP database and the Amcarelab exome database, respectively. Thus, the estimated prevalence interval of ATTRv in mainland China was 18.9/100,000-74,9/100,000. Conclusion: The present study demonstrated that the previous prevalence was greatly underestimated using traditional methods. Therefore, raising awareness of the disease is essential for recognizing ATTRv in its early stage.

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.

Enlarged cross-sectional area in peripheral nerves in Swedish patients with hereditary V30M transthyretin amyloidosis

INTRODUCTION

In hereditary transthyretin amyloidosis (ATTRv), two different fibrillar forms causing the amyloid deposition, have been identified, displaying substantially cardiac or neuropathic symptoms. Neuropathic symptoms are more frequent in early-onset patients, whereas late-onset patients, besides cardiac symptoms, seem to develop carpal tunnel syndrome, more often. With ultrasonography (US) of peripheral nerves, it is possible to distinguish structural changes, and enlarged cross-sectional area (CSA). The main purpose of this study was, for the first time, to elucidate US of peripheral nerves in Swedish ATTRv patients at an early stage of the disease, and to evaluate possible early enlarged CSA.

MATERIAL AND METHODS

This prospective study included first visit data of 13 patients, aged 30-88 years, of which 11 with late-onset age. All had a positive V30M mutation. Eight men and six women (aged 28-74 years) served as controls.

RESULTS

Significantly enlarged CSA was seen in ATTRv patients for the tibial nerve at the ankle (p = .001), the sural nerve (p < .001), the peroneal nerve at the popliteal fossa (p = .003), and the ulnar nerve at the middle upper arm (p = .007).

CONCLUSION

US of peripheral nerves could be a valuable tool in disease evaluation and could facilitate monitoring of disease progression.

Hereditary Transthyretin Amyloidosis with Polyneuropathy: Monitoring and Management

Our aim in this review is to discuss current treatments and investigational products and their effect on patients with hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) and provide suggestions for monitoring disease progression and treatment efficacy.

High Hereditary Transthyretin-Related Amyloidosis Prevalence in Crete

Background and Objectives

Our goal was to study hereditary transthyretin-related amyloidosis (hATTR) in Crete, Greece.

Methods

We aimed at ascertaining all hATTR cases in Crete, an island of 0.62 million people. For this, we evaluated patients with polyneuropathy, autonomic involvement, cardiomyopathy, and/or ophthalmopathy suggestive of hATTR, who presented to the physicians of this study or were referred to them by other physicians. Genetic analyses were performed on all patients suspected of suffering from hATTR. We included in our observational longitudinal cohort study all individuals, residents of Crete, who, during the study period (1993–2019), were found to carry a pathogenic TTR variant.

Results

Over the past 27 years, 30 individuals (15 female patients, 15 male patients), from 12 apparently unrelated families, were diagnosed with hATTR, whereas evaluation of their offspring identified 5 asymptomatic TTR pathogenic variant carriers. The most prevalent TTR variant detected was p.Val50Met, affecting 19 patients (11 female patients, 8 male patients) and causing a rather consistent phenotype characterized by predominant polyneuropathy of early adult onset (median age of symptom onset: 30 years; range: 18–37 years). Specifically, patients affected by the p.Val50Met TTR variant experienced progressive sensorimotor disturbances, involving mainly the lower extremities, associated with autonomic and/or gastrointestinal dysfunction. The second most frequent TTR variant was p.Val114Ala, found in 10 patients (4 female patients, 6 male patients) who were affected at an older age (median age of symptom onset: 70 years; range: 54–78 years). This variant caused a predominantly cardiomyopathic phenotype, manifested by congestive heart failure and associated with peripheral neuropathy, carpal tunnel syndrome, and/or autonomic involvement. In these patients, cardiac amyloid deposition was detected on 99m-technetium pyrophosphate scintigraphy and/or heart biopsy. The third TTR variant (p.Arg54Gly) was found in a 50-year-old male patient with ophthalmopathy due to vitreous opacities and positive family history for visual loss. As 22 patients were alive at the end of the study, we calculated the hATTR prevalence in Crete to be 35 cases per 1 million inhabitants.

Discussion

Our study revealed that the prevalence of hATTR in Crete is one of the world's highest. Three different pathogenic TTR variants causing distinct clinical phenotypes were identified in this relatively small population pool.

A pilot study of nailfold capillaroscopy in hereditary transthyretin amyloidosis

Nailfold capillaroscopy (NFC) is a safe and non-invasive imaging tool for evaluating microvascular abnormalities. This retrospective cross-sectional study aimed to analyze the NFC outcomes and clinical characteristics in patients and an asymptomatic carrier with transthyretin (TTR) gene mutation. The participants consist of eight patients with genetically and clinically confirmed hereditary amyloidogenic transthyretin (ATTRv) amyloidosis and one asymptomatic carrier. The TTR gene mutant forms of six male and three female participants from six families were Asp38Ala (five patients), Lys35Asn (three patients), and Ala36Pro (one patient). All participants showed decreased capillary density, dilatated capillaries, and destructed architecture in NFC. Early progression identification of a carrier to patients with symptoms is a major concern from a therapeutic viewpoint in ATTRv amyloidosis. Therefore, further studies with a larger number of subjects will be needed to determine the use of NFC as an early detection tool.

Monitoring the Patient with Retinal Angiopathy Associated with Hereditary Transthyretin Amyloidosis: Current Perspectives

Retinal angiopathy associated with hereditary transthyretin amyloidosis (ATTRv), if untreated, may lead to irreversible vision loss. Our purpose was to systematically review the clinical and imaging features of retinal angiopathy associated with ATTRv and assemble a monitoring approach for these patients. All types of original research studies reporting clinical and imaging findings on retinal angiopathy associated with ATTRv were included. The most common clinical findings were tortuous retinal vessels, microaneurysms, retinal hemorrhages, sheathing of retinal vessels, whitish amyloid deposits along retinal arteries, obliteration of retinal vessels, vitreous hemorrhage, retinal and iris neovascularization. The most relevant imaging findings were hyperautofluorescence of perivessel amyloid deposits; delayed arterial filling, vascular leakage, and retinal ischemia on fluorescein angiography; late hypercyanescence along the choroidal arteries on indocyanine green angiography; perivascular hyperreflective material, needle-shaped deposits on the retinal surface and macular edema on optical coherence tomography (OCT) and attenuated retinal vascular network on OCT-angiography. ATTRv patients should be strictly followed to detect and treat retinal angiopathy, avoiding complications. Both panretinal photocoagulation and intravitreal anti-vascular endothelial growth factor have been used to treat retinal angiopathy in ATTRv. In an individual that presents with retinal angiopathy of unknown etiology, ATTRv should be considered as in the differential diagnosis, even out of the initial core countries. The prognostic value of subclinical findings, namely in OCT-A, is not yet established.

Neuromuscular Complications of Systemic Amyloidosis

Systemic amyloidosis is characterized by extracellular deposition of insoluble fibrillar proteins in multiple tissues, frequently at a distance from the site of synthesis. The 2 most common forms, light chain (AL) and transthyretin (ATTR) amyloidosis can cause peripheral neuropathy and, rarely, myopathy. Diagnosis can be challenging, and abundant suspicion is required to identify patients. As neurological manifestations of amyloidosis may precede involvement of other organs by several years, recognizing amyloid neuropathy and myopathy are crucial, especially in this new and exciting era of effective therapies for AL and ATTR neuropathy. This review will focus on the neuromuscular manifestations of AL and ATTR amyloidosis, diagnostic approaches, and recent advances in the treatment of amyloid neuropathy.

Unique Phenotypes With Corresponding Pathology in Late-Onset Hereditary Transthyretin Amyloidosis of A97S vs. V30M

Objective

Hereditary transthyretin amyloidosis (ATTRv) encompasses different phenotypes among various genotypes. The analysis of the natural history and risk factors of faster progression in different genotypes would refine the treatment strategy.

Methods

The clinical manifestations of ATTRv from A97S (p.A117S) of Taiwanese and late-onset V30M (p.V50M) of Japanese were compared. An autopsy study of A97S was performed.

Results

There existed three unique features in the A97S cohort compared to the V30M cohort: (1) dysphagia, (2) carpal tunnel syndrome (CTS), and (3) onset age. First, dysphagia was common in A97S (53.4%) but not in V30M and served as a contributor to fast disease progression. All phases of swallowing were affected. In the autopsy pathology, there were extensive amyloid deposits in the viscera and nerves of the tongue, larynx, and esophagus. In A97S, 45 patients (43.3%) had a history of CTS before the onset of length-dependent symptoms by 3 years. The amyloid deposition was more prominent in the median nerve than that in the transverse carpal ligament. The onset age at different stages was younger in the A97S cohort than the V30M cohort by 4–5 years.

Conclusion

These phenotypic characteristics together with autopsy pathology in A97S are distinct from V30M. Early dysphagia in A97S correlated with fast progression. In A97S, median neuropathy leading to CTS might be in a continuous spectrum of ATTRv course rather than an independent disease entity. Such observations may serve as a foundation to explore and analyze unique phenotypes among various genotypes.

Plasmin activity promotes amyloid deposition in a transgenic model of human transthyretin amyloidosis

Cardiac ATTR amyloidosis, a serious but much under-diagnosed form of cardiomyopathy, is caused by deposition of amyloid fibrils derived from the plasma protein transthyretin (TTR), but its pathogenesis is poorly understood and informative in vivo models have proved elusive. Here we report the generation of a mouse model of cardiac ATTR amyloidosis with transgenic expression of human TTR^S52P. The model is characterised by substantial ATTR amyloid deposits in the heart and tongue. The amyloid fibrils contain both full-length human TTR protomers and the residue 49-127 cleavage fragment which are present in ATTR amyloidosis patients. Urokinase-type plasminogen activator (uPA) and plasmin are abundant within the cardiac and lingual amyloid deposits, which contain marked serine protease activity; knockout of α₂-antiplasmin, the physiological inhibitor of plasmin, enhances amyloid formation. Together, these findings indicate that cardiac ATTR amyloid deposition involves local uPA-mediated generation of plasmin and cleavage of TTR, consistent with the previously described mechano-enzymatic hypothesis for cardiac ATTR amyloid formation. This experimental model of ATTR cardiomyopathy has potential to allow further investigations of the factors that influence human ATTR amyloid deposition and the development of new treatments.

ATTR amyloidosis causes heart failure through the accumulation of misfolded transthyretin in cardiac muscle. Here the authors report a mouse model of ATTR amyloidosis and demonstrate the involvement of protease activity in ATTR amyloid deposition.

Characterization of population genetic structure of hereditary transthyretin amyloidosis in Bulgaria

The hereditary transthyretin amyloidosis (ATTRv amyloidosis) is an autosomal dominant genetic disease characterized by amyloid formation in different tissues due to pathogenic variants in the TTR gene. Great heterogeneity in the penetrance and manifestation of ATTRv amyloidosis is observed. In Bulgaria, the most common TTR pathogenic variant is Glu89Gln. Other TTR pathogenic variants are also found - Val30Met, Ser77Phe, Gly47Glu and Ser52Pro. There is a proven founder effect for the Glu89Gln variant, thus the aim of the present study is to investigate the founder effect for the other TTR pathogenic variants in Bulgaria. Haplotype analysis was performed by using microsatellite markers close to the TTR gene. DNA samples from ATTRv amyloidosis patients and their healthy relatives were analyzed. Theoretical haplotype reconstruction was done with Arlequin v.3.01 software. The age of the most recent common ancestor (hypothetical founder) for the studied variants was calculated with the DMLE 2.2 software. In addition, DBS screening among 100 Roma newborns was done for the Gly47Glu TTR variant via direct Sanger sequencing. The reconstructed haplotypes of the patients were compared to their healthy relatives and to a control group of 40 healthy individuals. The results showed a possible founder effect for each of the studied variants. The Val30Met haplotype was compared to published haplotype data for this variant and no similarity was found. The result from the DBS screening showed no pathogenic TTR variants in exon 2 of the gene, so we considered the presence of the Gly47Glu variant in our population a sporadic event. With this study, we succeeded to gain a more complete picture of the population genetics of ATTRv amyloidosis in Bulgaria and made another step towards a more detailed understanding of the disease epidemiology.

Transthyretin amyloid-related transitory events (TARTEs): Descriptive analysis of clinical, imagiological, and neurophysiological features

Transthyretin-related familial amyloid polyneuropathy (ATTR-FAP) is a multisystemic disorder inherited as an autosomal dominant trait. Transitory events in ATTR-FAP patients are a feature of this disorder and remain poorly depicted in the literature. We aimed to describe a case series of ATTR-FAP patients who presented to our department with transitory events and document the clinical, neuroimaging and neurophysiological characteristics of the events. We collected data from eight patients carrying the Val30Met ATTR-FAP variant. We registered a total of 23 events. Of the eight patients, seven had been submitted to hepatic transplant. The events were either TIA-like or seizures, often followed by prolonged language, motor or sensory impairment. In 9 (39%) of the events, the patients presented with fever, but an infection was only found in 5 (21%). Cerebrospinal fluid analysis was performed in 5 patients. EEG was abnormal in at least 1 event in 7 of the 8 patients. Brain MRI was performed in 3 patients during the acute stage and showed no acute lesions. Although the etiology of these events remains unclear, brain MRI performed in the acute phase of acute TIA-like events and the EEG abnormalities, argues in favor of regional brain dysfunction due to amyloid deposition. Focal neurological episodes should be considered in long-term duration Val30Met ATTR-FAP patients, who present with acute neurological deficits or seizures.

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.

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.

Disease Modifying Treatments for Transthyretin Amyloidosis

ABSTRACT

The transthyretin (TTR) amyloidoses result from misfolding of the protein leading to fibril formation and aggregation as amyloid deposits in predominantly the cardiovascular and nervous systems. Cardiac involvement can manifest as heart failure, arrhythmias, and valvular disease. Neurologic involvement can cause sensorimotor polyneuropathies, mononeuropathies, and dysautonomia. Previously, treatment has focused on management of these symptoms and disease sequelae, with a high rate of mortality due to the absence of disease modifying therapies. In this manuscript, we review novel treatments focusing on three mechanistic pathways: (1) silencing of the TTR gene to suppress production, (2) stabilizing of TTR tetramers to prevent misfolding, or (3) disrupting of existing TTR amyloid fibrils to promote reabsorption.

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.

Subclinical retinal angiopathy associated with hereditary transthyretin amyloidosis - assessed with optical coherence tomography angiography

BACKGROUND

Retinal angiopathy is a known ocular manifestation of hereditary transthyretin amyloidosis (ATTRv). Optical coherence tomography angiography (OCT-A) is a recent noninvasive imaging technique, used in other retinal vascular diseases. Our purpose was to analyse subclinical changes in retinal vessels, with OCT-A, in patients with ATTRv amyloidosis.

METHODS

Observational cross-sectional study in Centro Hospitalar e Universitário do Porto in the cohort of patients with genetic diagnosis of ATTRv. Patients were included if they had just one eye with scalloped iris (the other eye without scalloped iris), postulating eyes were at different stages, in the same patient. Patients were excluded if they had other manifestations of ocular ATTRv amyloidosis, namely clinical retinal angiopathy and/or vitreous opacities. The group of eyes with scalloped iris were compared with eyes without scalloped iris, using paired tests. Values are shown as Δ = mean difference between groups; p = p-value, d = Cohen's d for effect size measurement.

RESULTS

Twenty-four patients (24 eyes in each group) were included. Mean age was 46.5 ± 5.0 years. Eyes with scalloped iris showed attenuated retinal vascular network: larger foveal avascular zone (FAZ) area (Δ = +0.02 mm², p = 0.002, d = 0.70); decreased foveal vascular density (Δ = -3.57%, p = 0.001, d = -0.75); superficial (Δ = -1.50%, p = 0.049, d = -0.43) and deep (Δ = -2.53%, p = 0.023, d = -0.50) plexus vascular density. Acircularity index was superior in scalloped iris eyes (Δ = 0.04, p = 0.004, d = -0.65), representing an abnormal FAZ morphology.

CONCLUSION

Scalloped iris in ATTRv eyes are associated with a more advanced subclinical retinal angiopathy, than eyes without scalloped iris. Our results identify for the first time and in vivo, early changes in retinal vessels in ATTRv amyloidosis. Henceforward, OCT-A may play a role in the evaluation of ATTRv patients oculopathy and the effectiveness of future eye targeting treatments.

Pupillometry: An objective test to assess endocular hereditary transthyretin amyloidosis

OBJECTIVE

To automatically study the pupillary light reflex in patients with hereditary transthyretin-associated amyloidosis (hATTR).

METHODS

Prospective cross-sectional observational study in patients with hATTR with unilateral scalloped iris. Pupillary light reflex of scalloped iris eyes (21 eyes) were compared with non-scalloped iris eyes (21 eyes, paired eyes of the same patients) and also with a control group of 20 healthy eyes, using static and dynamic pupillometry with the Metrovision^® MonPack One.

RESULTS

No patient presented evident neurological involvment of the cranial nerves. No significant differences were found in the pupillary diameters under standardized lighting conditions (static pupillometry) among groups. In dynamic pupillometry, the amplitude of contraction, the velocity of contraction and the velocity of dilation were statistically significantly lower in eyes with scalloped iris, comparing both with the contralateral non-scalloped iris eyes (p < 0.001 for all) and with eyes from healthy subjects (p < 0.05 for all).

CONCLUSION

A scalloped iris reflects a more advanced endocular hATTR and it is associated with an altered pupillary light reflex. Pupillometry may be a quick, simple, and portable test to objectively evaluate ocular amyloid deposition in hATTR eyes. Pupillary light reflex may not be reliable to evaluate neurological dysfunction in these patients.

Modulation of the Mechanisms Driving Transthyretin Amyloidosis

Transthyretin (TTR) amyloidoses are systemic diseases associated with TTR aggregation and extracellular deposition in tissues as amyloid. The most frequent and severe forms of the disease are hereditary and associated with amino acid substitutions in the protein due to single point mutations in the TTR gene (ATTRv amyloidosis). However, the wild type TTR (TTR wt) has an intrinsic amyloidogenic potential that, in particular altered physiologic conditions and aging, leads to TTR aggregation in people over 80 years old being responsible for the non-hereditary ATTRwt amyloidosis. In normal physiologic conditions TTR wt occurs as a tetramer of identical subunits forming a central hydrophobic channel where small molecules can bind as is the case of the natural ligand thyroxine (T₄). However, the TTR amyloidogenic variants present decreased stability, and in particular conditions, dissociate into partially misfolded monomers that aggregate and polymerize as amyloid fibrils. Therefore, therapeutic strategies for these amyloidoses may target different steps in the disease process such as decrease of variant TTR (TTRv) in plasma, stabilization of TTR, inhibition of TTR aggregation and polymerization or disruption of the preformed fibrils. While strategies aiming decrease of the mutated TTR involve mainly genetic approaches, either by liver transplant or the more recent technologies using specific oligonucleotides or silencing RNA, the other steps of the amyloidogenic cascade might be impaired by pharmacologic compounds, namely, TTR stabilizers, inhibitors of aggregation and amyloid disruptors. Modulation of different steps involved in the mechanism of ATTR amyloidosis and compounds proposed as pharmacologic agents to treat TTR amyloidosis will be reviewed and discussed.

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.

Sex Differences in the Phenotype of Transthyretin Cardiac Amyloidosis Due to Val122Ile Mutation: Insights from Noninvasive Pressure-Volume Analysis

BACKGROUND

Transthyretin cardiac amyloidosis (ATTR-CA) is an under-recognized cause of heart failure with preserved ejection fraction. In the United States, the valine-to-isoleucine substitution (Val122Ile) is the most common inherited variant. Data on sex differences in presentation and outcomes of Val122Ile associated ATTR-CA are lacking.

METHODS AND RESULTS

In a retrospective, single-center study of 73 patients diagnosed with Val122Ile associated ATTR-CA between 2001 and 2018, sex differences in clinical and echocardiographic data at the time of diagnosis were evaluated. Pressure-volume analysis using noninvasive single beat techniques was used to compare chamber performance. Compared with men (n = 46), women (n = 27) were significantly older at diagnosis, 76 years vs 69 years; P < .001. The end-systolic pressure-volume relationship, 5.1 mm Hg*m²/mL vs 4.3 mm Hg*m²/mL; P = .27, arterial elastance, 5.5 mm Hg*m²/mL vs 5.7 mm Hg*m²/mL; P = .62, and left ventricular capacitance were similar between sexes as was pressure-volume areas indexed to a left ventricular end-diastolic pressure of 30 mm Hg, a measure of overall pump function. The 3-year mortality rates were also similar, 34% vs 43%; P = .64.

CONCLUSIONS

Despite being significantly older at time of diagnosis with Val122Ile associated ATTR-CA, women have similar overall cardiac chamber function and rates of mortality to men, suggesting a less aggressive disease trajectory. These findings should be confirmed with longitudinal studies.

Hereditary Transthyretin Amyloidosis: Clinical Presentation and Management Updates

Hereditary transthyretin amyloidosis, once a rare progressive neuropathy and/or cardiomyopathy, is now recognized with increasing worldwide frequency, various phenotypes, and over 130 gene mutations identified to date. This inherited disorder develops as a result of mutated transthyretin amyloid aggregation and systematic deposition throughout the body. With increasing knowledge about the pathophysiology of this disease, new disease-modifying therapies are being developed. In addition to slowing progression, these new agents were found to improve quality of life and reduce the severity of neuropathic symptoms. Two new gene-modifying therapies recently received Food and Drug Administration approval following the positive results from phase III trials. These include an antisense oligonucleotide, inotersen, and small interfering RNA, patisiran, which were reported to reduce the production of transthyretin and had promising safety profiles. Additional novel therapies are being explored with hopes to prolong survival. Therefore, early diagnosis of this treatable disorder has become increasingly important in clinical practice.

Clinical characteristics in patients with hereditary amyloidosis with Glu54Gln transthyretin identified in the Romanian population

BACKGROUND

In Romania, 23 patients have been diagnosed with hereditary transthyretin amyloidosis (ATTRh), 18 of whom have the Glu54Gln mutation. This retrospective cohort included all patients with Glu54Gln-mutated ATTRh who were diagnosed in Romania from 2005 to 2018.

RESULTS

Of 18 patients, 10 were symptomatic, five were asymptomatic carriers and three died during the study. All originated from North-East Romania. Median age at symptom onset was 45 years; median age at death was 51 years. All patients had cardiac involvement, including changes in biomarkers (mean N-terminal-pro B-type natriuretic peptide: 2815.6 pg/ml), electrocardiography (15% atrial fibrillation, 38% atrioventricular block, 31% right bundle block), and echocardiography (mean interventricular septum: 16 mm, mean left ventricular ejection fraction: 49%). Scintigraphy showed myocardial radiotracer uptake in all patients. In addition, 92% of patients had polyneuropathy at diagnosis and 53% had carpal tunnel syndrome; 69% exhibited orthostatic hypotension and 31% suffered from diarrhea. No renal or liver involvement was observed.

CONCLUSIONS

This is the largest Glu54Gln-mutated ATTRh cohort diagnosed to date, and to our knowledge the first describing this variant worldwide. Clinical features of this variant are early onset, neurological and cardiac involvement, aggressive disease progression and short survival. Early diagnosis and therapeutic intervention have potential to improve prognosis in ATTRh.

The frequency of central nervous system complications in the Cypriot cohort of ATTRV30M neuropathy transplanted patients

BACKGROUND

Hereditary transthyretin amyloidosis (ATTR) is a hereditary, sensorimotor and autonomic neuropathy caused by deposits of mutated transthyretin (TTR). The commonest TTR mutation is V30M (ATTRV30M) with patients usually living for about 10 years after disease onset. Liver transplantation (LT) until recently was considered the standard treatment.

OBJECTIVE AND METHODS

This study aims to assess the frequency of CNS complications in post-LT patients from the Cypriot cohort. Epidemiological data were collected for all genetically confirmed ATTRV30M neuropathy patients diagnosed at CING since 1992, and CNS-associated symptoms were assessed and evaluated by two neurology specialists.

RESULTS

Out of the 48 transplanted patients, 10 (20.8%) presented with a CNS complication. All patients had ocular involvement, mainly glaucoma (7/10). Eight presented with transient focal neurological episodes (TFNEs), with expressive dysphasia being reported by four of them. The mean time of TFNE-emergence was 16.6 years after the LT. Three died from cerebral hemorrhage.

CONCLUSIONS

CNS complications in post-LT ATTRV30M patients are not rare and usually manifest themselves at a time that surpasses the mean time the patients would have survived without a LT. CNS involvement is associated with increased mortality, due to cerebral hemorrhage.

Clinicopathological correlations of sural nerve biopsies in TTR Val30Met familial amyloid polyneuropathy

Familial amyloid polyneuropathy with the substitution of methionine for valine at position 30 in the TTR gene is the most common type of hereditary transthyretin amyloidosis. Although several authors have previously reported a size-dependent fibre loss, predominantly involving unmyelinated and small-diameter myelinated fibres, the mechanisms of nerve fibre loss have not been fully understood. In this study, we establish the morphometric pattern of peripheral neuropathy in patients with familial amyloid polyneuropathy and asymptomatic mutation carriers in the biopsies from our archive and correlated the pathological findings with clinical features. A total of 98 patients with familial amyloid polyneuropathy and 37 asymptomatic mutation carriers (TTR Val30Met mutation), aged between 17 and 84 years, who underwent sural nerve biopsy between 1981 and 2017 at Centro Hospitalar Universitário do Porto were studied. Thirty-one controls were included for comparison. The median age at nerve biopsy was 26.0 [interquartile range = 23.5–39.5] years for asymptomatic mutation carriers, 45.0 [35.0–60.0] years for patients with familial amyloid polyneuropathy and 44.0 [30.0–63.0] years for controls. The median duration between nerve biopsy and symptoms’ onset was 7.0 [3.3–11.8] years (range: 1–27 years) in the asymptomatic carriers. Most patients were in an earlier disease stage (93% with a polyneuropathy disability scale ≤2). Patients had loss of small and myelinated fibres compared with both asymptomatic carriers and controls (P < 0.001), whereas asymptomatic carriers showed loss of small myelinated fibres when compared with controls (P < 0.05). The loss of myelinated fibres increased with disease progression (P < 0.001), and patients in more advanced clinical stage showed more frequent amyloid deposition in the nerve (P = 0.001). There was a positive correlation between large myelinated fibre density and time to symptoms’ onset in the asymptomatic carriers that developed early-onset form of the disease (r = 0.52, P < 0.01). In addition, asymptomatic carriers with amyloid deposition already present in sural nerve biopsies developed symptoms earlier than those with no amyloid (P < 0.01). In conclusion, this study confirms that the loss of small fibre size is an initial event in familial amyloid polyneuropathy, already present in asymptomatic gene carriers, starting several years before the onset of symptoms. We show for the first time that large myelinated fibres’ loss and amyloid deposition are pathological features that correlate independently with short period to the onset of symptoms for asymptomatic carriers that developed early-onset form of the disease. These findings are therapeutically relevant, as it would allow for a better interpretation of the role of disease-modifying agents in transthyretin familial amyloid polyneuropathy.

Prevalence of hereditary transthyretin amyloid polyneuropathy in idiopathic progressive neuropathy in conurban areas

Background

Hereditary transthyretin amyloidosis (ATTR amyloidosis) is a rare, genetically heterogenous, and clinically variable autosomal dominant disease that severely reduces life expectancy. As treatment options grow, a proper diagnostic approach is mandatory especially in non-endemic regions with diverse genetic backgrounds.

Methods

We examined 102 neuropathy patients at a German neuromuscular centre. Common causes of polyneuropathy were ruled out by medical history and extensive laboratory testing to define a cohort of patients with progressive polyneuropathy classified as idiopathic. Molecular genetic testing of the entire TTR gene was performed, and the detected amyloidogenic and non-amyloidogenic variants were associated with the observed clinical phenotypes and results of prior diagnostic testing.

Results

Two of 102 patients tested positive for amyloidogenic mutations (p.Ile127Val and p.Glu81Lys), while a variant of unknown significance, p.Glu26Ser, was found in 10 cases. In both positive cases, previous negative biopsy results were proved by gene sequencing to be false negative. In case of the p.Glu81Lys mutation we detected clinical presentation (combination of severe polyneuropathy and cardiomyopathy), ethnic background (patient of polish origin, mutation only reported in Japanese families before), and disease course clearly differed from well-known cases of the same mutation in the literature.

Conclusions

In conclusion, transthyretin hereditary amyloid polyneuropathy (ATTR-PN) should be considered in cases of otherwise idiopathic polyneuropathy. Sequencing of the four exons of the TTR gene should be considered the key step in diagnosis, while tissue biopsy possibly leads to false negative results.

Monoallelic expression of the TTR gene as a contributor to the age at onset and penetrance of TTR-related amyloidosis

TTR-related amyloidosis (ATTR) is manifested in two allelic forms: familial amyloid polyneuropathy (TTR-FAP) and cardiomyopathy (TTR-FAC), both caused by mutations in the TTR gene. The most prevalent mutation in Bulgaria is p.Glu89Gln. Markedly different age at onset and disease penetrance is noticed in Bulgarian p.Glu89Gln cases even in a single family or between genetically identical twins. The present study aimed to evaluate the transcription profile of the TTR gene in order to better understand the difference in disease onset and penetrance. Six p.Glu89Gln positive families were selected from our registry, based on intrafamilial differences in disease onset and penetrance. Plasma and urine specimens were collected from 13 patients and subjected to transcription analysis. Both mutant and wild type transcripts were visualized in a mixed transcription profile, which is the traditional model of autosomal gene expression. The results from a relative quantification of the mutant versus wild type transcript showed presence of the mutant transcript between 0.14 and 1.14 times against the wild type. In addition, monoallelic expression signature was also detected. Based on our results we propose a model of natural selection, which includes age-related allele exclusion or suppression: predominant expression of a wild type (at an early age) and mutant (at the process of ageing) alleles. The intrafamilial differences in disease onset and penetrance need to be considered in genetic counselling and in follow-up of mutation carriers.

RE-INTERVENTION IN DE NOVO VITREOUS OPACITIES AFTER PARS PLANA VITRECTOMY IN FAMILIAL AMYLOIDOTIC POLYNEUROPATHY TTR VAL30METPORTUGUESE PATIENTS

PURPOSE

To report management of de novo vitreous amyloid opacities after previous pars plana vitrectomy in familial amyloidotic polyneuropathy transthyretin Val30Met.

METHODS

This work is a retrospective observational consecutive case series of five eyes of four patients. Demographic data, transthyretin mutation involved, age at the beginning of disease, duration of disease, treatment (liver transplant or tafamidis), time between vitrectomy and re-intervention, and ophthalmologic changes were evaluated. Surgical re-intervention included phacoemulsification with intraocular lens implantation in phakic eyes, re-vitrectomy as complete as possible with posterior capsulectomy, and internal limiting membrane peeling if wrinkling of internal retinal surface was present.

RESULTS

All patients had transthyretin Val30Met mutation, and three were women. Mean age of onset of the disease was 52 ± 11.0 years, and average evolution time of the disease was 8 years. Three patients had been submitted to liver transplant 4, 9, and 15 years before. Time between first vitrectomy and surgical re-intervention was longer than 2 years in all cases. Two eyes had amyloid deposits on anterior lens surface and pupillary border with scalloped pupil. Two eyes were phakic. Glaucoma was present in two eyes; one of them had previous trabeculectomy. All cases had vitreous opacities behind posterior lens capsule and at vitreous base area. After re-intervention, no further recurrence was observed (average follow-up of 10 months).

CONCLUSION

De novo vitreous amyloid opacities may occur several years after pars plana vitrectomy. Amyloid deposition in vitreous cavity was observed only in strong vitreous adherence locations (behind posterior lens capsule and at vitreous base area). The authors expect that this procedure, an extensive re-vitrectomy associated with posterior capsulectomy, will prevent de novo vitreous amyloid opacities.

Predictive model of response to tafamidis in hereditary ATTR polyneuropathy

BACKGROUNDThe hereditary transthyretin (TTR) amyloidoses are a group of diseases for which several disease-modifying treatments are now available. Long-term effectiveness of these therapies is not yet fully known. Moreover, the existence of alternative therapies has resulted in an urgent need to identify patient characteristics that predict response to each therapy.METHODSWe carried out a retrospective cohort study of 210 patients with hereditary TTR amyloidosis treated with the kinetic stabilizer tafamidis (20 mg qd). These patients were followed for a period of 18-66 months, after which they were classified by an expert as responders, partial responders, or nonresponders. Correlations between baseline demographic and clinical characteristics, as well as plasma biomarkers and response to therapy, were investigated.RESULTS34% of patients exhibited an almost complete arrest of disease progression (classified by an expert as responders); 36% had a partial to complete arrest in progression of some but not all disease components (partial responders); whereas the remaining 30% continued progressing despite therapy (nonresponders). We determined that disease severity, sex, and native TTR concentration at the outset of treatment were the most relevant predictors of response to tafamidis. Plasma tafamidis concentration after 12 months of therapy was also a predictor of response for male patients. Using these variables, we built a model to predict responsiveness to tafamidis.CONCLUSIONOur study indicates long-term effectiveness for tafamidis, a kinetic stabilizer approved for the treatment of hereditary TTR amyloidosis. Moreover, we created a predictive model that can be potentially used in the clinical setting to inform patients and clinicians in their therapeutic decisions.

Hereditary transthyretin amyloidosis: a model of medical progress for a fatal disease

Hereditary amyloidogenic transthyretin (ATTRv) amyloidosis with polyneuropathy (also known as familial amyloid polyneuropathy) is a condition with adult onset caused by mutation of transthyretin (TTR) and characterized by extracellular deposition of amyloid and destruction of the somatic and autonomic PNS, leading to loss of autonomy and death. This disease represents a model of the scientific and medical progress of the past 30 years. ATTRv amyloidosis is a worldwide disease with broad genetic and phenotypic heterogeneity that presents a diagnostic challenge for neurologists. The pathophysiology of the neuropathy is increasingly understood and includes instability and proteolysis of mutant TTR leading to deposition of amyloid with variable lengths of fibrils, microangiopathy and involvement of Schwann cells. Wild-type TTR is amyloidogenic in older individuals. The main symptoms are neuropathic, but the disease is systemic; neurologists should be aware of cardiac, eye and kidney involvement that justify a multidisciplinary approach to management. Infiltrative cardiomyopathy is usually latent but present in half of patients. Disease-modifying therapeutics that have been developed include liver transplantation and TTR stabilizers, both of which can slow progression of the disease and increase survival in the early stages. Most recently, gene-silencing drugs have been used to control disease in the more advanced stages and produce some degree of improvement.

Brazilian consensus for diagnosis, management and treatment of transthyretin familial amyloid polyneuropathy

Transthyretin familial amyloid polyneuropathy is an autosomal dominant inherited sensorimotor and autonomic polyneuropathy, which if untreated, leads to death in approximately 10 years. In Brazil, liver transplant and tafamidis are the only disease-modifying treatments available. This review consists of a consensus for the diagnosis, management and treatment for transthyretin familial amyloid polyneuropathy from the Peripheral Neuropathy Scientific Department of the Brazilian Academy of Neurology. The first and last authors produced a draft summarizing the main views on the subject and emailed the text to 10 other specialists. Relevant literature on this subject was reviewed by each participant and used for the individual review of the whole text. Each participant was expected to review the text and send a feedback review by e-mail. Thereafter, the 12 panelists got together at the city of Fortaleza, discussed the controversial points, and reached a consensus for the final text.

Pacemaker implantation in familial amyloid polyneuropathy: when and for whom?

BACKGROUND

Despite the important role of cardiac pacing in preventing syncope and sudden cardiac death in familial amyloid polyneuropathy (FAP), we lack clear guidelines as to the ideal timing and indications for permanent pacemaker implantation.

PURPOSE

The purpose of this study was to evaluate the ideal timing for pacemaker implantation in FAP patients submitted to liver transplantation.

METHODS

Retrospective study of 258 FAP patients submitted to liver transplantation between 1992 and 2012. Comparison of three groups: (A) patients without pacemaker (N = 122); (B) patients submitted to pacemaker implantation after liver transplantation, with documented conduction disorders (N = 73); and (C) patients submitted to "prophylactic" pacemaker implantation before transplantation, (N = 73). Patients were followed up for 12.2 ± 6.7 years.

RESULTS

The majority of patients (57%) were referred for pacemaker implantation, which occurred before liver transplantation in 50% of cases. Patients who required pacemaker after transplantation presented significantly higher Machado-Joseph Score during pre-transplant evaluation than those who did not require pacemaker (24 ± 10 vs 20 ± 10, p = .025), and also exhibited higher levels of hepatic cytolysis enzymes and hyperbilirubinemia. The most common indication for permanent pacemaker was first degree atrioventricular block, with a mean time between transplantation and pacemaker implantation of 8.7 ± 4.2 years. During long-term follow-up, all-cause mortality was 27% and was lowest in the group submitted to pacemaker implantation only after liver transplantation (p = 0.002).

CONCLUSION

The majority of FAP patients submitted to liver transplantation will need a pacemaker at some time of follow-up. However, it seems that there is no benefit in "prophylactic" cardiac pacing before liver transplantation.

C1QA and C1QC modify age-at-onset in familial amyloid polyneuropathy patients

Objectives

Transthyretin (TTR) familial amyloid polyneuropathy (FAP) (OMIM 176300) shows a variable age‐at‐onset (AO), including within families. We hypothesized that variants in C1QA and C1QC genes, might also act as genetic modifiers of AO in TTR‐FAP Val30Met Portuguese patients.

Methods

We analyzed DNA samples of 267 patients (117 families). To search for variants, all exons and flanking regions were genotyped by automated sequencing. We used generalized estimating equations (GEEs) to take into account the non‐independency of AO among relatives. Intensive in silico analyses were performed, using various software to assess miRNAs target sites, splicing sites, transcription factor binding sites alterations, and gene–gene interactions.

Results

Two variants for C1QA gene, GA genotype of rs201693493 (P < 0.001) and CT genotype of rs149050968 (P < 0.001), were significantly associated with later AO. In silico analysis demonstrated, that rs201693493 may alter splicing activity. Regarding C1QC, we found three statistically significant results: GA genotype of rs2935537 (P = 0.003), GA genotype of rs201241346 (P < 0.001) and GA genotype of rs200952686 (P < 0.001). The first two were associated with earlier AO, whereas the third was associated with later‐onset.

Interpretation

C1QA was associated with later onset, whereas C1QC may have a double role: variants may confer earlier or later AO. As found in a study in Cyprus, we confirmed the role of complement C1Q genes (and thus of inflammation) as modulator of AO in Portuguese patients with TTR‐FAP Val30Met.