Hereditary Amyloidosis: Insights Into a Fibrinogen A Variant Protein.

Amyloidosis are a group of diseases in which soluble proteins aggregate and deposit in fibrillar conformation extracellularly in tissues. The effectiveness of therapeutic strategies depends on the specific protein involved, being crucial to accurately determine its nature. Moreover, following the diagnosis, the search for the mutation within relatives allows the clinical advice. Here we report the precise diagnosis and explored the possible reasons of the structural pathogenicity for a renal amyloidosis related to a fibrinogen Aα-chain variant. Whole-exome sequencing and GATK calling pipeline were leveraged to characterize the protein variant present in a patient with kidney failure. Bioinformatics strategies were applied to suggest potential explanations of the variants aggregation. Our pipeline allowed the identification of a single-point variant of fibrinogen Aα-chain, which opened the possibility of curative transplantation. In silico structural analysis suggested that the pathogenicity of the variant may be attributed to a heightened susceptibility to yield a peptide prone to deposit as an oligomer with a ß-sheet structure. Exploiting the comprehensive coverage of whole-genome sequencing, we managed to fill a vacant stage in the diagnosis of hereditary amyloidosis and to stimulate the advancement in biomedicine.

Clinical comparison of V122I genotypic variant of transthyretin amyloid cardiomyopathy with wild-type and other hereditary variants: a systematic review.

V122I genotype variant (pV142I) is the most common hereditary transthyretin amyloidosis (hATTR) in the USA, with 3-3.5% of African-Americans being the carriers of this mutation. We aimed to compare baseline clinical features, cardiac parameters, and mortality in V122I-ATTR with the wild-type ATTR and other hATTR subtypes. We systematically searched PubMed/Medline and Google Scholar databases to identify relevant studies from inception to 10th September, 2020 reporting phenotypic, echocardiographic, and/or laboratory parameters in patients with hereditary and wild types of cardiac amyloidoses. A total of 2843 patients from 7 individual studies with 67-100% males and an overall follow-up duration of 51.6 ± 30.4 months were identified. The mean age of diagnosis among wild-type ATTR patients was 77 years, followed by 71.2 and 65 years in V122I and T60A group patients, respectively. V122I patients were mostly black, had a poor quality of life, and highest mortality risk compared with other subtypes. Merely, the presence of V122I mutation was identified as an independent predictor of mortality. V30M subtype correlated with the least severe cardiac disease and a median survival duration comparable with T60A subtype. V122I ATTR is an aggressive disease, prevalent in African-Americans, and is associated with a greater morbidity and mortality, which is partly attributed to its misdiagnosis and/or late diagnosis. Current advances in non-invasive studies to diagnose hATTR coupled with concurrent drug therapies have improved quality of life and provide a survival benefit to these patients.

Changes in nerve conduction studies predate clinical symptoms onset in early onset Val30Met hereditary ATTR amyloidosis.

BACKGROUND AND PURPOSE: Hereditary amyloidosis related to transthyretin (ATTR) is a rare and progressive disease that, despite the phenotypic heterogeneity, a length-dependent sensorimotor axonal neuropathy (ATTR-PN) is the classic hallmark. Timely diagnosis is paramount for early treatment implementation. METHODS: Sixty-nine asymptomatic gene carriers (Val30Met) were assessed during a 4-year period to identify those remaining asymptomatic versus those converting to ATTRV30M-PN. Conversion to symptomatic was defined as presenting with two definite symptoms of ATTRV30M-PN. Composite neurophysiological scores of sensory (SNS), motor (MNS), and sympathetic skin response (SSRS) amplitudes were used to assess neuropathy progression. We used mixed-effects modeling and ordinal logistic regression to assess neurophysiological evolution over time. RESULTS: Of all asymptomatic gene carriers, 55.1% (n = 38/69) converted over the period of this analysis. The progression of the SNS relative to baseline was different between groups (asymptomatic gene carriers vs. converters), the decline being greater in the converter group (time × group interaction p = 0.040), starting about 2 years before symptom onset. No significant change occurred regarding MNS or SSRS. Moreover, the percentage of cases with an annual decline on the SNS of at least 25%, gradually and significantly increased in the converter group, representing a 1.92 increase in risk of developing symptoms for those with such reduction on the last evaluation. CONCLUSIONS: A simple composite neurophysiological sum score can predict the onset of ATTRV30M-PN symptoms by as much as 2 years, highlighting the importance of a systematic follow-up of asymptomatic gene carriers, allowing a timely diagnosis, and management of symptomatic disease.

A Brief Journey through Protein Misfolding in Transthyretin Amyloidosis (ATTR Amyloidosis).

Transthyretin (TTR) amyloidogenesis involves the formation, aggregation, and deposition of amyloid fibrils from tetrameric TTR in different organs and tissues. While the result of amyloidoses is the accumulation of amyloid fibrils resulting in end-organ damage, the nature, and sequence of the molecular causes leading to amyloidosis may differ between the different variants. In addition, fibril accumulation and toxicity vary between different mutations. Structural changes in amyloidogenic TTR have been difficult to identify through X-ray crystallography; but nuclear magnetic resonance spectroscopy has revealed different chemical shifts in the backbone structure of mutated and wild-type TTR, resulting in diverse responses to the cellular conditions or proteolytic stress. Toxic mechanisms of TTR amyloidosis have different effects on different tissues. Therapeutic approaches have evolved from orthotopic liver transplants to novel disease-modifying therapies that stabilize TTR tetramers and gene-silencing agents like small interfering RNA and antisense oligonucleotide therapies. The underlying molecular mechanisms of the different TTR variants could be responsible for the tropisms to specific organs, the age at onset, treatment responses, or disparities in the prognosis.

TRANSTHYRETIN AMYLOIDOSIS THERAPIES: GUIDING THE FUTURE.

Transthyretin (TTR) amyloidosis (ATTR) is a progressive condition characterized by multiorgan accumulation of amyloid deposits composed of transthyretin (TTR) fibrils. Over the past decades, despite being a rare disease, ATTR amyloidosis has enabled top-tier therapeutics. In the 90s, organ transplantation was the mainstream therapeutic option and fostered distinct approaches, such as combined liver-heart transplant and domino (sequential) liver transplantation. Likewise, several TTR molecule stabilizers were developed successfully. Over the past decade, oriented genetic therapies emerged to prevent, control, and, surprisingly, reverse amyloid deposition. Silencing the TTR gene using different strategies is flourishing, and ongoing trials continue to evaluate diverse approaches to optimize their application. The following perspective describes the currently available treatments for ATTR amyloidosis and the prospects on the potential application of these strategies in other medical fields.

Autonomic involvement in hereditary transthyretin amyloidosis (hATTR amyloidosis).

PURPOSE: Hereditary transthyretin amyloidosis (hATTR amyloidosis) is a progressive disease primarily characterized by adult-onset sensory, motor, and autonomic neuropathy. In this article, we discuss the pathophysiology and principal findings of autonomic neuropathy in hATTR amyloidosis, the most common methods of assessment and progression, and its relation as a predictive risk factor or a measure of progression in the natural history of the disease. METHODS: A literature search was performed using the terms "autonomic neuropathy," "dysautonomia," and "autonomic symptoms" in patients with hereditary transthyretin amyloidosis and familial amyloid polyneuropathy. RESULTS: Various scales to measure autonomic function have been employed, particularly within the major clinical trials, to assess novel therapies for the disease. Most of the evaluations were taken from diabetic clinical trials. Questionnaires include the COMPASS-31 and Norfolk QOL autonomic nerve function domain, whereas clinical evaluations comprise HRDB and the orthostatic tolerance test. Several treatment options are being employed although only diflunisal and tafamidis have reported improvement in the autonomic abnormalities. CONCLUSIONS: Autonomic nerves are often affected before motor nerve impairment, and dysautonomia may support the diagnosis of hATTR amyloidosis when differentiating from other adult-onset progressive neuropathies and from other types of amyloidosis. Most of the progression of autonomic dysfunction is seen in early stages of the disease, commonly before motor impairment or affection of the overall quality of life. Unfortunately, there is no current single standardized approach to evaluate dysautonomia in hATTR amyloidosis.

Typing of hereditary renal amyloidosis presenting with isolated glomerular amyloid deposition.

BACKGROUND: The commonly used methods for amyloid typing include immunofluorescence or immunohistochemistry (IHC), which sometimes may come with diagnostic pitfalls. Mass spectrometry (MS)-based proteomics has been recognized as a reliable technique in amyloid typing. CASE PRESENTATION: We reported two middle-aged patients who presented with proteinuria, hypertension and normal renal function, and both had a family history of renal diseases. The renal biopsies of both patients revealed renal amyloidosis with the similar pattern by massive exclusively glomerular amyloid deposition. The IHC was performed by using a panel of antibodies against the common types of systemic amyloidosis, and demonstrated co-deposition of fibrinogen Aα chain and apolipoprotein A-I in the glomerular amyloid deposits of each patient. Then the MS on amyloid deposits captured by laser microdissection (LMD/MS) and genetic study of gene mutations were investigated. The large spectra corresponding to ApoA-I in case 1, and fibrinogen Aα chain in case 2 were identified by LMD/MS respectively. Further analysis of genomic DNA mutations demonstrated a heterozygous mutation of p. Trp74Arg in ApoA-I in case 1, and a heterozygous mutation of p. Arg547GlyfsTer21 in fibrinogen Aα chain in case 2. CONCLUSIONS: The current study revealed that IHC was not reliable for accurate amyloid typing, and that MS-based proteomics and genetic analysis were essential for typing of hereditary amyloidosis.

Impact of Genetic Testing in Transthyretin (ATTR) Cardiac Amyloidosis.

PURPOSE OF REVIEW: The review's main focus centers on the genetics of hereditary cardiac amyloidosis, highlighting the opportunities and challenges posed by the widespread availability of genetic screening and diagnostic cardiac imaging. RECENT FINDINGS: Advancements in cardiac imaging, heightened awareness of the ATTR amyloidosis diagnosis, and greater access to genetic testing have all led to an increased appreciation of the prevalence of ATTR cardiac amyloidosis. Elucidation of the TTR molecular structure and effect of mutations on TTR function have allowed for novel TTR therapy development leading to clinical implementation of transthyretin stabilizers and transthyretin gene silencers. The transthyretin amyloidoses are a diverse group of protein misfolding disorders with cardiac and peripheral/autonomic nervous system manifestations due to protein deposition. Genetic screening allows for the early identification of asymptomatic TTR mutation carriers. With the advent of TTR-specific therapeutics, clinical guidance is necessary for the management of individuals with mutations in the TTR gene without evidence of disease.

Clinical outcomes after preimplantation genetic diagnosis of patients with Corino de Andrade disease (familial amyloid polyneuropathy).

The aim of this study was to determine whether patients with transthyretin-related hereditary amyloidosis (V30M), after transplantation or under tafamidis treatment, have normal gamete reproductive capacity. A retrospective analysis was carried out of all preimplantation genetic diagnosis (PGD) cycles performed in patients with the V30M mutation. The groups analysed were: total cases with V30M, female cases with V30M and male cases with V30M. Detailed demographic, stimulation, embryological, clinical and newborn outcomes were evaluated. Comparisons revealed that patients have a high likelihood of achieving a live birth per PGD treatment cycle (48%). This is the first large report on patients with the V30M mutation treated with PGD. The high rate of live birth obtained should represent a strong stimulus for patients to use PGD as it proved to be effective and safe. As a neurodegenerative disease that leads to death, it is of maximum importance that it could be eradicated using PGD in order to definitively avoid the transmission of the disease.

Hereditary amyloidosis related to transthyretin V30M: disease progression in treated and untreated patients.

BACKGROUND AND PURPOSE: Hereditary amyloidosis related to transthyretin V30M (hATTR V30M) is a progressive length-dependent sensorimotor axonal neuropathy. We aimed to compare the disease progression of treated [liver transplantation (LT) or tafamidis] versus untreated patients with hATTR V30M. METHODS: A total of 81 patients with hATTR V30M were included: 27 untreated, 25 treated with LT and 29 undergoing tafamidis treatment. Neuropathy was assessed at baseline, 12, 24 and 36 months after study entry. We evaluated disease stage, modified polyneuropathy disability (mPND) score and a composite neurophysiological score comprised of sensory and motor conduction parameters. The effect of treatment on disease progression was analysed using linear mixed-effects modelling. RESULTS: At baseline, patients from the untreated group were older (P < 0.01) and those in the LT group had longer disease duration than those in the tafamidis group (P < 0.05). Gender, mPND and motor scores at study entry were equal in the three groups; however, the untreated group had lower sensory scores compared with the tafamidis group (P < 0.01). During the 3-year follow-up period, progression to stage II of the disease was seen only in the untreated group. The progression on mPND, sensory and motor scores was significantly higher in the untreated patients. When treated groups were compared, the LT group had lower rates of composite neurophysiological score progression. However, the sensory score outcome was similar between tafamidis responders and LT patients. CONCLUSION: Both LT and tafamidis therapy modified the natural history of hATTR V30M by reducing neuropathy progression.

Novel Type of Renal Amyloidosis Derived from Apolipoprotein-CII.

Amyloidosis is characterized by extracellular deposition of misfolded proteins as insoluble fibrils. Most renal amyloidosis cases are Ig light chain, AA, or leukocyte chemotactic factor 2 amyloidosis, but rare hereditary forms can also involve the kidneys. Here, we describe the case of a 61-year-old woman who presented with nephrotic syndrome and renal impairment. Examination of the renal biopsy specimen revealed amyloidosis with predominant involvement of glomeruli and medullary interstitium. Proteomic analysis of Congo red-positive deposits detected large amounts of the Apo-CII protein. DNA sequencing of the APOC2 gene in the patient and one of her children detected a heterozygous c.206A→T transition, causing an E69V missense mutation. We also detected the mutant peptide in the proband's renal amyloid deposits. Using proteomics, we identified seven additional elderly patients with Apo-CII-rich amyloid deposits, all of whom had kidney involvement and histologically exhibited nodular glomerular involvement. Although prior in vitro studies have shown that Apo-CII can form amyloid fibrils and that certain mutations in this protein promote amyloid fibrillogenesis, there are no reports of this type of amyloidosis in humans. We propose that this study reveals a new form of hereditary amyloidosis (AApoCII) that is derived from the Apo-CII protein and appears to manifest in the elderly and preferentially affect the kidneys.

Transthyretin Cardiac Amyloidosis.

PURPOSE OF REVIEW: Transthyretin (TTR)-related cardiac amyloidosis is a progressive infiltrative cardiomyopathy that mimics hypertensive, hypertrophic heart disease and may go undiagnosed. Transthyretin-derived amyloidosis accounts for 18% of all cases of cardiac amyloidosis. Thus, the study's purpose is to provide a comprehensive review of transthyretin cardiac amyloidosis. RECENT FINDINGS: Wild-type transthyretin (ATTRwt) protein causes cardiac amyloidosis sporadically, with 25 to 36% of the population older than 80 years of age are at risk to develop a slowly progressive, infiltrative amyloid cardiomyopathy secondary to ATTRwt. In contrast, hereditary amyloidosis (ATTRm) is an autosomal dominant inherited disease associated with more than 100 point mutations in the transthyretin gene and has a tendency to affect the heart and nervous system. Up to 4% of African-Americans carry the Val122Ile mutation in the transthyretin gene, the most prevalent cause of hereditary cardiac amyloidosis in the USA. Identifying transthyretin cardiac amyloidosis requires increased awareness of the prevalence, signs and symptoms, and diagnostic tools available for discrimination of this progressive form of cardiomyopathy associated with left ventricular hypertrophy. While there are no FDA-approved medical treatments, investigation is underway on agents to reduce circulating mutated transthyretin.

"Red-flag" symptom clusters in transthyretin familial amyloid polyneuropathy.

Transthyretin familial amyloid polyneuropathy (TTR-FAP) is a rare, progressive, life-threatening, hereditary disorder caused by mutations in the transthyretin gene and characterized by extracellular deposition of transthyretin-derived amyloid fibrils in peripheral and autonomic nerves, heart, and other organs. TTR-FAP is frequently diagnosed late because the disease is difficult to recognize due to phenotypic heterogeneity. Based on published literature and expert opinion, symptom clusters suggesting TTR-FAP are reviewed, and practical guidance to facilitate earlier diagnosis is provided. TTR-FAP should be suspected if progressive peripheral sensory-motor neuropathy is observed in combination with one or more of the following: family history of a neuropathy, autonomic dysfunction, cardiac hypertrophy, gastrointestinal problems, inexplicable weight loss, carpal tunnel syndrome, renal impairment, or ocular involvement. If TTR-FAP is suspected, transthyretin genotyping, confirmation of amyloid in tissue biopsy, large- and small-fiber assessment by nerve conduction studies and autonomic system evaluations, and cardiac testing should be performed.

In vivo detection of nerve injury in familial amyloid polyneuropathy by magnetic resonance neurography.

Transthyretin familial amyloid polyneuropathy is a rare, autosomal-dominant inherited multisystem disorder usually manifesting with a rapidly progressive, axonal, distally-symmetric polyneuropathy. The detection of nerve injury by nerve conduction studies is limited, due to preferential involvement of small-fibres in early stages. We investigated whether lower limb nerve-injury can be detected, localized and quantified in vivo by high-resolution magnetic resonance neurography. We prospectively included 20 patients (12 male and eight female patients, mean age 47.9 years, range 26-66) with confirmed mutation in the transthyretin gene: 13 with symptomatic polyneuropathy and seven asymptomatic gene carriers. A large age- and sex-matched cohort of healthy volunteers served as controls (20 male and 20 female, mean age 48.1 years, range 30-73). All patients received detailed neurological and electrophysiological examinations and were scored using the Neuropathy Impairment Score-Lower Limbs, Neuropathy Deficit and Neuropathy Symptom Score. Magnetic resonance neurography (3 T) was performed with large longitudinal coverage from proximal thigh to ankle-level and separately for each leg (140 axial slices/leg) by using axial T2-weighted (repetition time/echo time = 5970/55 ms) and dual echo (repetition time 5210 ms, echo times 12 and 73 ms) turbo spin echo 2D sequences with spectral fat saturation. A 3D T2-weighted inversion-recovery sequence (repetition time/echo time 3000/202 ms) was acquired for imaging of the spinal nerves and lumbar plexus (50 axial slice reformations). Precise manual segmentation of the spinal/sciatic/tibial/common peroneal nerves was performed on each slice. Histogram-based normalization of nerve-voxel signal intensities was performed using the age- and sex-matched control group as normative reference. Nerve-voxels were subsequently classified as lesion-voxels if a threshold of >1.2 (normalized signal-intensity) was exceeded. At distal thigh level, where a predominant nerve-lesion-voxel burden was observed, signal quantification was performed by calculating proton spin density and T2-relaxation time as microstructural markers of nerve tissue integrity. The total number of nerve-lesion voxels (cumulated from proximal-to-distal) was significantly higher in symptomatic patients (20 405 ± 1586) versus asymptomatic gene carriers (12 294 ± 3199; P = 0.036) and versus controls (6536 ± 467; P < 0.0001). It was also higher in asymptomatic carriers compared to controls (P = 0.043). The number of nerve-lesion voxels was significantly higher at thigh level compared to more distal levels (lower leg/ankle) of the lower extremities (f-value = 279.22, P < 0.0001). Further signal-quantification at this proximal site (thigh level) revealed a significant increase of proton-density (P < 0.0001) and T2-relaxation-time (P = 0.0011) in symptomatic patients, whereas asymptomatic gene-carriers presented with a significant increase of proton-density only. Lower limb nerve injury could be detected and quantified in vivo on microstructural level by magnetic resonance neurography in symptomatic familial amyloid polyneuropathy, and also in yet asymptomatic gene carriers, in whom imaging detection precedes clinical and electrophysiological manifestation. Although symptoms start and prevail distally, the focus of predominant nerve injury and injury progression was found proximally at thigh level with strong and unambiguous lesion-contrast. Imaging of proximal nerve lesions, which are difficult to detect by nerve conduction studies, may have future implications also for other distally-symmetric polyneuropathies.

Pathological, biochemical, and biophysical characteristics of the transthyretin variant Y114H (p.Y134H) explain its very mild clinical phenotype.

Transthyretin (TTR) is a homotetrameric protein that must misfold in order to form amyloid fibrils. Misfolding includes rate limiting tetramer dissociation, followed by fast tertiary structural changes of the monomer that enable aggregation. Hereditary ATTR amyloidosis is an autosomal dominant genetic disorder with systemic deposition of amyloid fibrils induced by TTR gene mutation. We identified a rare Y114H (p.Y134H) TTR variant in a Japanese patient presenting with late-onset, very mild clinical course. The patient had an extremely low serum variant TTR concentration (18% of total TTR), whereas the composition of variant TTR was 55% in amyloid fibrils in tenosynovial tissues obtained at carpal tunnel release surgery. The amyloid fibril deposits in the ATTR Y114H patient had an altered structure compared with that in wild-type ATTR patients, as determined by luminescent conjugated poly/oligo-thiophene fluorescence spectroscopy. Biophysical studies using recombinant protein showed that Y114H TTR was markedly destabilized both thermodynamically and kinetically and was highly amyloidogenic in vitro. These data suggest that extremely low serum variant Y114H TTR concentration, probably due to endoplasmic reticulum-associated degradation of unstable variant TTR protein, protected this patient from severe amyloidosis, as self-assembly of the amyloidogenic intermediate is a concentration-dependent process.

Online registry for mutations in hereditary amyloidosis including nomenclature recommendations.

Hereditary systemic amyloidosis comprises a group of rare monogenic diseases inherited in an autosomal dominant fashion. It is associated with mutations in genes encoding eight different proteins, including transthyretin, apolipoprotein AI, apolipoprotein AII, lysozyme, fibrinogen A α-chain, cystatin C, gelsolin and beta-2-microglobulin. With support from the EU FP6 EURAMY project we have designed an online registry of genes and mutations in hereditary amyloidosis including their associated clinical phenotypes, with a view to having a single free online portal for the collection and distribution of this information. Users can search the registry by either mutation, phenotype or authors who have published or submitted mutations. It provides a submission form for reporting newly identified mutations. We also wanted to introduce nomenclature which complies with recommendations set out by Human Genome Variation Society and HUGO Gene Nomenclature Committee for description of new and known genetic variants. We hope this registry would be a useful and convenient tool for the medical and scientific community.

Hereditary transthyretin amyloidosis with hydrocephalus at 27 years old: A case report.

Hereditary transthyretin amyloidosis is autosomal dominant and results from mutations in the transthyretin gene. The Val30Met variant is the most common genetic mutation, although mutations vary within populations. More than 150 mutations in transthyretin have been reported; however, the Leu111Glu (p. Leu131Glu) mutation has been reported to date. We report the case of a 32-year-old Japanese male with a history of cerebral hemorrhage and hydrocephalus at age 27 years. The patient was referred to our department after his sibling had been diagnosed with hereditary transthyretin amyloidosis. Twelve-lead electrocardiography exhibited poor R progression, and transthoracic echocardiography showed normal findings. 99mTc-labelled pyrophosphate scintigraphy showed high accumulation in the heart. Histological tests using a right ventricular endomyocardial biopsy showed amyloid deposits and immunostaining only for transthyretin. Genetic analysis confirmed a novel missense variant, Leu111Glu, on the transthyretin gene. We diagnosed the patient with hereditary transthyretin amyloidosis, and the patient received genetic counseling. Patients with hereditary transthyretin amyloidosis carrying the Leu111Gln variant may present as a patient with a hydrocephalus-dominant phenotype. To the best of our knowledge, this is the first case report of the transthyretin Leu111Glu variant. Learning objective: Hereditary transthyretin amyloidosis with the Leu111Gln variant has not been previously reported in Japan. While cardiac involvement progresses without overt abnormal findings on electrocardiogram and echocardiogram, 99mTc-labelled pyrophosphate scintigraphy can be a useful tool for the early diagnosis of hereditary transthyretin amyloidosis. This mutation may result in a predominantly hydrocephalus phenotype, and organ damage is expected to progress rapidly. Therefore, early diagnosis and appropriate treatment are necessary.

Assessing the effectiveness and safety of Patisiran and Vutrisiran in ATTRv amyloidosis with polyneuropathy: a systematic review.

Background: Hereditary transthyretin (ATTRv) amyloidosis, a multifaceted disorder affecting multiple systems, substantially diminishes patients' physical capabilities and overall quality of life. Patisiran and Vutrisiran, two Ribonucleic acid (RNA) interference therapies, target reducing both pathogenic and wild-type transthyretin (TTR) protein levels. This systematic review assesses the effectiveness and safety of these treatments in managing ATTRv. Methods: A comprehensive, thorough literature search across databases including Embase, PubMed, Web of Science, Cochrane Central, and Google Scholar yielded 858 studies. Following removing duplicate and irrelevant articles, 676 distinct studies underwent review. These studies, conducted on a global scale, encompassed a range of methodologies, including clinical trials and indirect treatment comparisons. Results: Ten studies, spanning a total population of 756 patients, were selected for in-depth analysis. Patisiran and Vutrisiran consistently demonstrated significant improvements in primary and secondary endpoints related to neuropathy, quality of life, and cardiac function. Both medications were well-tolerated, with primarily mild to moderate adverse events. Indirect treatment comparison studies indicated Vutrisiran's superiority over Tafamidis in treating ATTRv amyloidosis. Conclusion: This systematic review recommends using Patisiran and Vutrisiran to treat ATTRv amyloidosis. The findings suggest that these RNA interference therapies improve neuropathy, quality of life, and cardiac symptoms. The results indicate sustained benefits over prolonged treatment, with satisfactory safety profiles. However, potential biases, conflicts of interest in the studies, and limited follow-up periods in some trials necessitate cautious interpretation. Future research should address these limitations and provide more robust evidence for the long-term efficacy and safety of Patisiran and Vutrisiran in ATTRv treatment.

Circulating transthyretin and retinol binding protein 4 levels among middle-age V122I TTR carriers in the general population.

BACKGROUND: Hereditary transthyretin cardiac amyloidosis (ATTRv-CA) has a long latency phase before clinical onset, creating a need to identify subclinical disease. We hypothesized circulating transthyretin (TTR) and retinol binding protein 4 (RBP4) levels would be associated with TTR carrier status and correlated with possible evidence of subclinical ATTRv-CA. METHODS: TTR and RBP4 were measured in blood samples from V122I TTR carriers and age-, sex- and race-matched non-carrier controls (1:2 matching) among Dallas Heart Study participants (phases 1 (DHS-1) and 2 (DHS-2)). Multivariable linear regression models determined factors associated with TTR and RBP4. RESULTS: There were 40 V122I TTR carriers in DHS-1 and 54 V122I TTR carriers in DHS-2. In DHS-1 and DHS-2, TTR was lower in V122I TTR carriers (p < .001 for both), and RBP4 in DHS-2 was lower in V122I TTR carriers than non-carriers (p = .002). Among V122I TTR carriers, TTR was negatively correlated with markers of kidney function, and limb lead voltage (p < .05 for both) and TTR and RBP4 were correlated with atrial volume in DHS-2 (p < .05). CONCLUSIONS: V122I TTR carrier status is independently associated with lower TTR and RBP4 in comparison with non-carriers. These findings support the hypothesis that TTR and RBP4 may correlate with evidence of subclinical ATTRv-CA.