Finnish gelsolin amyloidosis causes significant disease burden but does not affect survival: FIN-GAR phase II study

Analysis and insights of cardiac amyloidosis: novel perception of rare diseases in cardiology

BACKGROUND

Amyloidosis is a rare systemic disease, while cardiac amyloidosis (CA) is nothing more than a chronic disease that causes fatal damage to the structure and function of the heart. The pathogenesis of CA is elusive, the clinical manifestations are diverse and lack of specificity, and the treatment and prognosis of different subtypes vary widely. It is of great practical significance to deepen the understanding of CA.

OBJECTIVE AND METHODS

The clinical data of 39 patients with CA admitted to the First Affiliated Hospital of Gannan Medical University and Fujian Medical University Union Hospital from January 1, 2018 to March 1, 2024 were collected and retrospectively studied, and the clinical features, diagnosis, differentiation, treatment effects and prognosis of CA patients were analyzed. The Kaplan-Meier method was used for survival analysis. Meanwhile, the latest literature from PubMed was retrieved to systematically discuss the research progress in the diagnosis and treatment of CA. This paper is expected to provide novel and valuable references for the clinical and basic research of CA.

RESULTS

A total of 39 patients with CA were included in this study, including 23 males (58.97%) and 16 females (41.03%). The average age at diagnosis was 60.51±10.28 years old. In this study, 24 patients (61.54%) had anemia of different degrees, 19 patients (48.72%) were accompanied by abnormal elevation of cardiac troponin T (cTnT), and all patients (100%) had abnormal elevation of N-terminal pro-brain natriuretic peptide (NT-proBNP), and 28 patients (71.79%) had renal impairment. Typical electrocardiogram (ECG) findings in CA patients in this study show low voltage in limb leads, various types of atrioventricular block, various types of tachycardia, atrial fibrillation and poor R-wave progression. The representative results of ultrasonic cardiogram (UCG) showed: 1. Atrium were enlarged, and ventricular wall motion was weakened. 2. Septum and posterior walls of the ventricle were symmetrically thickened, and the myocardium showed speckled strong echo. 3. Mitral regurgitation (moderate to severe) and tricuspid regurgitation. 4. Widening of the pulmonary artery and pulmonary hypertension. Typical results of cardiac magnetic resonance imaging (MRI) of CA patients in this study showed that delayed gadolinium enhancement of the ventricular wall, with ventricular wall thickening to varying degrees and ventricle or atrium enlargement. The pathological manifestations of CA patients in this study were mostly Congo red staining (+) and deposition of eosinophilic amyloid in the affected organs or tissues. All CA patients included in this study received standardized treatment, the median follow-up time was 29.5 (range, 6.5-71) months, and at the latest follow-up, only 12 cases of 39 patients with CA were still alive, and 27 patients died in our study, all of which were due to uncontrollable progression of the disease and failed treatment. Our study showed that there is no statistical significance in the different age groups of the CA patients (P>0.05), while it was surprising that male CA patients had significantly worse overall survival (OS) than female patients. Correspondingly, patients who received chemotherapy and were accompanied with renal impairment had a worse prognosis than those who did not receive chemotherapy and had normal renal function (all P<0.05).

CONCLUSION

CA is a rare disease caused by systemic amyloidosis, the pivotal points of CA diagnosis and treatment as well as the premise for improving the long-term prognosis of CA patients are clear diagnosis and accurate typing. The treatment of CA also requires targeted individual treatment according to the subtype and etiology of CA patients, so as to maximize the prognosis of CA patients.

Epitope-specific antibody fragments block aggregation of AGelD187N, an aberrant peptide in gelsolin amyloidosis

Aggregation of aberrant fragment of plasma gelsolin, AGelD187N, is a crucial event underlying the pathophysiology of Finnish gelsolin amyloidosis, an inherited form of systemic amyloidosis. The amyloidogenic gelsolin fragment AGelD187N does not play any physiological role in the body, unlike most aggregating proteins related to other protein misfolding diseases. However, no therapeutic agents that specifically and effectively target and neutralize AGelD187N exist. We used phage display technology to identify novel single-chain variable fragments that bind to different epitopes in the monomeric AGelD187N that were further maturated by variable domain shuffling and converted to antigen-binding fragment (Fab) antibodies. The generated antibody fragments had nanomolar binding affinity for full-length AGelD187N, as evaluated by biolayer interferometry. Importantly, all four Fabs selected for functional studies efficiently inhibited the amyloid formation of full-length AGelD187N as examined by thioflavin fluorescence assay and transmission electron microscopy. Two Fabs, neither of which bound to the previously proposed fibril-forming region of AGelD187N, completely blocked the amyloid formation of AGelD187N. Moreover, no small soluble aggregates, which are considered pathogenic species in protein misfolding diseases, were formed after successful inhibition of amyloid formation by the most promising aggregation inhibitor, as investigated by size-exclusion chromatography combined with multiangle light scattering. We conclude that all regions of the full-length AGelD187N are important in modulating its assembly into fibrils and that the discovered epitope-specific anti-AGelD187N antibody fragments provide a promising starting point for a disease-modifying therapy for gelsolin amyloidosis, which is currently lacking.

Exploring clinical variability in gelsolin amyloidosis: Brazilian family case study with confocal microscopy

INTRODUCTION

Genetic mutations or inflammatory, degenerative, or neoplastic conditions can trigger amyloidosis. Hereditary gelsolin amyloidosis is a genetic disorder primarily marked by amyloid fibrils composed of misfolded gelsolin fragments.

CASE REPORT

We present three sisters with AGel amyloidosis, illustrating its clinical diversity. Patient 1, a 51-year-old, had bilateral ptosis, ocular discomfort, and dry eye syndrome due to cranial nerve involvement. Patient 2, a 53-year-old, experienced progressive bilateral visual impairment. Patient 3, a 50-year-old, exhibited right eye ectropion. Genetic analysis, with the identical mutation, heterozygous c.640G > A (p.Asp214Asn) mutation, confirmed AGel amyloidosis diagnoses, with common findings including lattice corneal amyloidosis, reduced corneal sensitivity, and recurrent corneal erosions. Neurological manifestations included ataxia and peripheral neuropathy, with skin abnormalities observed in patient 1. Ocular involvement severity and distribution varied among patients.

DISCUSSION

Common ocular and neurological manifestations validated AGel amyloidosis diagnoses, reinforcing its hereditary basis. Neurological symptoms highlighted the disorder's impact on various organ systems, while skin abnormalities contributed to ocular discomfort. Variable ocular involvement emphasized the disorder's heterogeneity. These patients emphasize hereditary gelsolin amyloidosis's clinical diversity and suggest potential environmental influences on disease expression. Genetic confirmation and confocal microscopy findings reaffirm the genetic basis while raising questions about assessing systemic disease severity, necessitating further investigation in larger cohorts. Ophthalmologists' specialized care is crucial for managing ocular symptoms, given the absence of a universal cure.

Amyloidosis and Amyloidogenesis: One Name, Many Diseases

Amyloidosis is a heterogenous group of disorders, caused by the deposition of insoluble fibrils derived from misfolded proteins in the extracellular space of various organs. These proteins have an unstable structure that causes them to misfold, aggregate, and deposit as amyloid fibrils with the pathognomonic histologic property of green birefringence when viewed under cross-polarized light after staining with Congo red. Amyloid fibrils are insoluble and degradation-resistant; resistance to catabolism results in progressive tissue amyloid accumulation. The outcome of this process is organ disfunction independently from the type of deposited protein, however there can be organ that are specifically targeted from certain proteins.

Non-Immunoglobulin Amyloidosis-Mediated Kidney Disease: Emerging Understanding of Underdiagnosed Entities

Amyloidosis is a complex group of rare disorders characterized by the deposition of misfolded proteins in the extracellular space of various tissues and organs, leading to progressive organ dysfunction. The kidneys constitute a very common site affected, most notably by immunoglobulin-mediated (light chain, heavy chain, and light and heavy chain amyloidosis), but other types that include serum amyloid A (AA) amyloidosis and leukocyte chemotactic factor 2 amyloidosis, along with mutant proteins in several hereditary forms of amyloidosis such as transthyretin, fibrinogen α-chain, gelsolin, lysozyme, and apolipoproteins AI/AII/AIV/CII/CIII amyloidosis have been incriminated as well. The clinical presentation is variable and can range from minimal proteinuria for leukocyte chemotactic factor 2 amyloidosis to a full-blown nephrotic syndrome for AA amyloidosis. Clinical correlation, genetic analysis, and adequate tissue typing through a kidney biopsy are essential to make the correct diagnosis, especially when a family history of amyloidosis is absent. Except for AA and transthyretin amyloidosis, the treatment is usually purely supportive. Kidney transplantation is an acceptable form of treatment for end-stage kidney disease in all types of non-Ig-mediated renal amyloidosis.

Amyloid fibril cytotoxicity and associated disorders

Misfolded proteins assemble into fibril structures that are called amyloids. Unlike usually folded proteins, misfolded fibrils are insoluble and deposit extracellularly or intracellularly. Misfolded proteins interrupt the function and structure of cells and cause amyloid disease. There is increasing evidence that the most pernicious species are oligomers. Misfolded proteins disrupt cell function and cause cytotoxicity by calcium imbalance, mitochondrial dysfunction, and intracellular reactive oxygen species. Despite profound impacts on health, social, and economic factors, amyloid diseases remain untreatable. To develop new therapeutics and to understand the pathological manifestations of amyloidosis, research into the origin and pathology of amyloidosis is urgently needed. This chapter describes the basic concept of amyloid disease and the function of atypical amyloid deposits in them.

Dynamic Reconstruction Using Bilateral Lengthening Temporalis Myoplasty for Facial Palsies in Patients with Hereditary Skin Laxity

Hereditary skin laxity is a rare condition, some cases of which are also referred to as cutis laxa, and those involving facial skin are considered a target for treatment by plastic surgery as patients present with an aged face, which can reduce their quality of life. In some of these patients, the facial nerve and muscles may be affected, and cause weakness of mimetic muscles. We performed one-stage bilateral lengthening temporalis myoplasty reanimation, followed by lower facial contouring with partial lower lip excision and hammock-shaped fascia grafting in two patients with hereditary facial skin laxity coexisting with facial palsy. The patient was a 63-year-old woman with hereditary gelsolin amyloidosis and a 64-year-old man who was diagnosed with oculopharyngeal muscular dystrophy. Postoperatively, a symmetrical facial contour was achieved in repose, and smiling with and without biting was possible. To our knowledge, there are no reports of dynamic smile reconstruction for facial weakness in patients with hereditary facial skin laxity. Although these patients may experience progressive loss of function of the trigeminal nerve and its innervating muscles, the static suspension effect of lengthening temporalis myoplasty can be expected to continue even if the temporal muscles lose their function in the future. We believe that, with careful patient selection, dynamic reconstruction is an option for progressive facial paralysis. In this article, we present the chronological history of two patients who underwent multiple plastic surgery procedures and discuss the importance of the role of plastic surgery in improving the quality of life under these conditions.

Familial cerebral amyloid disorders with prominent white matter involvement

Familial cerebral amyloid disorders are characterized by the accumulation of fibrillar protein aggregates, which deposit in the parenchyma as plaques and in the vasculature as cerebral amyloid angiopathy (CAA). Amyloid β (Aβ) is the most common of these amyloid proteins, accumulating in familial and sporadic forms of Alzheimer's disease and CAA. However, there are also a number of rare, hereditary, non-Aβ cerebral amyloidosis. The clinical manifestations of these familial cerebral amyloid disorders are diverse, including cognitive or neuropsychiatric presentations, intracerebral hemorrhage, seizures, myoclonus, headache, ataxia, and spasticity. Some mutations are associated with extensive white matter hyperintensities on imaging, which may or may not be accompanied by hemorrhagic imaging markers of CAA; others are associated with occipital calcification. We describe the clinical, imaging, and pathologic features of these disorders and discuss putative disease mechanisms. Familial disorders of cerebral amyloid accumulation offer unique insights into the contributions of vascular and parenchymal amyloid to pathogenesis and the pathways underlying white matter involvement in neurodegeneration. With Aβ immunotherapies now entering the clinical realm, gaining a deeper understanding of these processes and the relationships between genotype and phenotype has never been more relevant.

Clinical considerations in early-onset cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is an important cerebral small vessel disease associated with brain haemorrhage and cognitive change. The commonest form, sporadic amyloid-β CAA, usually affects people in mid- to later life. However, early-onset forms, though uncommon, are increasingly recognized and may result from genetic or iatrogenic causes that warrant specific and focused investigation and management. In this review, we firstly describe the causes of early-onset CAA, including monogenic causes of amyloid-β CAA (APP missense mutations and copy number variants; mutations of PSEN1 and PSEN2) and non-amyloid-β CAA (associated with ITM2B, CST3, GSN, PRNP and TTR mutations), and other unusual sporadic and acquired causes including the newly-recognized iatrogenic subtype. We then provide a structured approach for investigating early-onset CAA, and highlight important management considerations. Improving awareness of these unusual forms of CAA amongst healthcare professionals is essential for facilitating their prompt diagnosis, and an understanding of their underlying pathophysiology may have implications for more common, late-onset, forms of the disease.

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.

Familial amyloidosis of the Finnish type: clinical and neurophysiological features of two index cases

Familial amyloidosis of the Finnish type (FAF) is a rare multisystemic disorder caused by mutations in the gelsolin gene. The clinical presentation is typically characterised by a triad of ophthalmic, neurological and dermatological findings. FAF has been reported in several countries, primarily in Finland and recently in Portugal. We report the first genetically confirmed cases of FAF from two unrelated families in our neuromuscular outpatient clinic. Gelsolin gene sequencing revealed the heterozygous gelsolin mutation (c.640G>A). The clinical features and the neurophysiological studies of two index patients and their relatives are presented. Obtaining an early diagnosis can be challenging, but FAF should be considered in the differential diagnosis of progressive bilateral facial neuropathy, even if there is no known Finnish ancestor.

Rational Design of a Peptidomimetic Inhibitor of Gelsolin Amyloid Aggregation

Gelsolin amyloidosis (AGel) is characterized by multiple systemic and ophthalmic features resulting from pathological tissue deposition of the gelsolin (GSN) protein. To date, no cure is available for the treatment of any form of AGel. More than ten single-point substitutions in the GSN gene are responsible for the occurrence of the disease and, among them, D187N/Y is the most widespread variant. These substitutions undergo an aberrant proteolytic cascade, producing aggregation-prone peptides of 5 and 8 kDa, containing the Gelsolin Amyloidogenic Core, spanning residues 182-192 (GAC_182-192). Following a structure-based approach, we designed and synthesized three novel sequence-specific peptidomimetics (LB-5, LB-6, and LB-7) built on a piperidine-pyrrolidine unnatural amino acid. LB-5 and LB-6, but not LB-7, efficiently inhibit the aggregation of the GAC_182-192 amyloidogenic peptides at sub-stoichiometric concentrations. These peptidomimetics resulted also effective in vivo, in a C. elegans-based assay, in counteracting the proteotoxicity of aggregated GAC_182-192. These data pave the way to a novel pharmacological strategy against AGel and also validate a toolbox exploitable in other amyloidogenic diseases.

Renal amyloidosis: a new time for a complete diagnosis

Amyloidoses are a group of disorders in which soluble proteins aggregate and deposit extracellularly in tissues as insoluble fibrils, causing organ dysfunction. Clinical management depends on the subtype of the protein deposited and the affected organs. Systemic amyloidosis may stem from anomalous proteins, such as immunoglobulin light chains or serum amyloid proteins in chronic inflammation or may arise from hereditary disorders. Hereditary amyloidosis consists of a group of rare conditions that do not respond to chemotherapy, hence the identification of the amyloid subtype is essential for diagnosis, prognosis, and treatment. The kidney is the organ most frequently involved in systemic amyloidosis. Renal amyloidosis is characterized by acellular pathologic Congo red-positive deposition of amyloid fibrils in glomeruli, vessels, and/or interstitium. This disease manifests with heavy proteinuria, nephrotic syndrome, and progression to end-stage kidney failure. In some situations, it is not possible to identify the amyloid subtype using immunodetection methods, so the diagnosis remains indeterminate. In cases where hereditary amyloidosis is suspected or cannot be excluded, genetic testing should be considered. Of note, laser microdissection/mass spectrometry is currently the gold standard for accurate diagnosis of amyloidosis, especially in inconclusive cases. This article reviews the clinical manifestations and the current diagnostic landscape of renal amyloidosis.

Prevalence, characteristics, and mortality of patients with transthyretin amyloid cardiomyopathy in the Nordic countries

Aims

Transthyretin amyloid cardiomyopathy (ATTR‐CM) is a progressive condition caused by deposition of transthyretin amyloid fibrils in the heart and is associated with poor quality of life and a shortened lifespan. This study aimed to describe the prevalence, clinical characteristics, and mortality of patients with ATTR‐CM, using multiple national health registers in Denmark, Finland, Norway, and Sweden.

Methods and results

Transthyretin amyloid cardiomyopathy patients were identified during 2008–2018 using a combination of diagnosis codes for amyloidosis and heart disease and were matched to patients with non‐ATTR heart failure (HF). An identical study design was used in each country to facilitate comparison and aggregation of results. A total of 1930 ATTR‐CM patients were identified from national health registers in the four countries. In 2018, prevalence of ATTR‐CM per 100 000 inhabitants ranged from 1.4 in Denmark to 5.0 in Sweden; a steep increase over time was observed in Sweden and Norway. Median survival from diagnosis was 30 months for ATTR‐CM patients and 67 months for matched HF patients. Survival was significantly lower for female than for male ATTR‐CM patients (median survival: 22 and 36 months), while no significant difference was observed in the HF cohort.

Conclusions

This study provides the first nationwide estimates of the prevalence, clinical characteristics, and mortality of patients with ATTR‐CM, using identical study design across several countries. Findings corroborate previous case series showing high mortality in ATTR‐CM, two‐fold higher than for other HF patients and higher in women than men, highlighting the need for more precise and early diagnosis to reduce the disease burden.

Hearing problems in patients with hereditary gelsolin amyloidosis

BACKGROUND

Gelsolin amyloidosis (AGel amyloidosis) is a hereditary form of systemic amyloidosis featuring ophthalmological, neurological and cutaneous symptoms. Previous studies based mainly on patients' self-reporting have indicated that hearing impairment might also be related to the disease, considering the progressive cranial neuropathy characteristic for AGel amyloidosis. In order to deepen the knowledge of possible AGel amyloidosis-related hearing problems, a clinical study consisting of the Speech, Spatial and Qualities of Hearing Scale (SSQ) questionnaire, clinical examination, automated pure-tone audiometry and a speech-in-noise test was designed.

RESULTS

Of the total 46 patients included in the study, eighteen (39%) had self-reported hearing loss. The mean scores in the SSQ were 8.2, 8.3 and 8.6 for the Speech, Spatial and Qualities subscales, respectively. In audiometry, the mean pure tone average (PTA) was 17.1 (SD 12.2) and 17.1 (SD 12.3) dB HL for the right and left ears, respectively, with no difference to gender- and age-matched, otologically normal reference values. The average speech reception threshold in noise (SRT) was - 8.2 (SD 1.5) and - 8.0 (SD 1.7) dB SNR for the right and left ears, respectively, which did not differ from a control group with a comparable range in PTA thresholds.

CONCLUSION

Although a significant proportion of AGel amyloidosis patients experience subjective difficulties in hearing there seems to be no peripheral or central hearing impairment at least in patients up to the age of 60 years.

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.

Severe ocular involvement in hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis is a rare subtype of hereditary systemic amyloidosis. An old male presented with the characteristic triad of symptoms, including bilateral facial palsy, cutis laxa, and corneal lattice amyloidosis. The diagnosis was confirmed by the detection of the mutation in gelsolin gene located on chromosome 9. Although the presenting symptoms were highly suggestive of the disease, reports of severe ocular involvement are scarce in the literature.

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.

The long and winding road to target protein misfolding in cardiovascular diseases

BACKGROUND

In the last decades, cardiovascular diseases (CVD) have remained the first leading cause of mortality and morbidity in the world. Although several therapeutic approaches have been introduced in the past, the development of novel treatments remains an important research goal, which is hampered by the lack of understanding of key mechanisms and targets. Emerging evidences in recent years indicate the involvement of misfolded proteins aggregation and the derailment of protein quality control in the pathogenesis of cardiovascular diseases. Several potential interventions targeting protein quality control have been translated from the bench to the bedside to effectively employ the misfolded proteins as promising therapeutic targets for cardiac diseases, but with trivial results.

DESIGN

In this review, we describe the recent progresses in preclinical and clinical studies of protein misfolding and compromised protein quality control by selecting and reporting studies focusing on cardiovascular diseases including cardiomyopathies, cardiac amyloidosis, atherosclerosis, atrial fibrillation and thrombosis.

RESULTS

In preclinical models, modulators of several molecular targets (eg heat shock proteins, unfolded protein response, ubiquitin protein system, autophagy and histone deacetylases) have been tested in various conditions with promising results although lacking an adequate transition towards clinical setting.

CONCLUSIONS

At present, no therapeutic strategies have been reported to attenuate proteotoxicity in patients with CVD due to a lack of specific biomarkers for pinpointing upstream events in protein folding defects at a subclinical stage of the diseases requiring an intensive collaboration between basic scientists and clinicians.