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

Clinical features of hereditary transthyretin amyloidosis-polyneuropathy with transthyretin Ala97Ser(p.Ala117Ser) mutation in South Mainland China

OBJECTIVE

Our study aimed to report the clinical features and epidemiological characteristics of hereditary transthyretin amyloidosis-polyneuropathy(ATTRv-PN) with TTR Ala97Ser(p.Ala117Ser) mutation from South Mainland China.

METHODS

We identified 21 patients from 20 families diagnosed with Ala97Ser ATTRv-PN based on strict clinical and electrophysiological criteria from three centers. Clinical and laboratory data were retrospectively retrieved for analysis.

RESULTS

A gender imbalance was noted with a male-to-female ratio of 18:3. All patients showed late onset, with the age of onset at 56.5 ± 7.2 years. The predominant initial symptom, reported by 15 patients (71.4%), was numbness. Paraesthesia was present in all patients. Eighteen patients (85.7%) had autonomic dysfunction. Cardiac, renal, and ocular dysfunctions were noted in 17 (80.9%), 4(19.0%), and 4(19.0%) patients, respectively. Nerve conduction studies have shown axonal-type sensorimotor polyneuropathy. The decline in sensory nerve action potentials was more noticeable than in compound muscle action potentials. The nerve damage present in the lower limbs was more severe than that in the upper limbs. Nerve biopsy revealed positive Congo red staining in 11/15 patients (73.3%).

CONCLUSION

ATTRv-PN appears relatively rare in South Mainland China, with our study providing the largest cohort of Ala97Ser mutation cases to date. We found a significant founder effect by combining the clinical and demographic characteristics. That helps us understand the gene's transmission pathway and lays the foundation for carrier screening and tertiary prevention and control. We also propose a new scoring model and demonstrate that this model allows the profiling of different genotypes of ATTRv-PN, facilitating early clinical detection and diagnosis.

A retrospective observational analysis of the real-world care pathway of people with hereditary transthyretin amyloidosis with polyneuropathy in Italy

BACKGROUND

This retrospective observational study described the epidemiology and the burden on the Italian healthcare service (SSN) of patients with polyneuropathy (PN) associated with hereditary transthyretin amyloidosis (ATTRv).

RESEARCH DESIGN AND METHODS

From the Fondazione ReS (Ricerca e Salute) administrative healthcare database (~5.5 million inhabitants in 2021), patients were identified as having ATTRv-PN in 2021 if they had received treatments for ATTRv-PN under SSN reimbursement (i.e. tafamidis, patisiran, or inotersen) from 1 January 2014 to 31 December 2021 (index date in 2021). Demographics and comorbidities at the baseline, healthcare resource consumption, and related direct costs reimbursed by the SSN throughout the one-year follow-up were described.

RESULTS

In 2021, 36 patients with ATTRv-PN (prevalence: 7.4/1,000,000) were identified (males were 83.3%; patients with ≥2 comorbidities were 61.1%; the mean age was 73 ± 8 years). During follow-up, of patients, 91.7% received drugs for ATTRv-PN; >50% received antiepileptics and acid suppressants; 22.2% were admitted to overnight hospitalizations; 30.6% accessed the emergency department; 97.2% received local outpatient specialist care. The per patient mean annual cost was € 122,017; drugs for ATTRv-PN accounted for 94.7% of the total expenditure.

CONCLUSIONS

This study of real-world patients with ATTRv-PN showed a high rate of comorbidities, and substantial direct healthcare and economic burdens on the SSN.

Hereditary Transthyretin Amyloidosis in Israel: Genetic Landscape and Clinical Characteristics

BACKGROUND

Hereditary transthyretin (ATTRv) amyloidosis is a rare, adult-onset autosomal-dominant disorder caused by pathogenic variants in the transthyretin (TTR) gene. Data about relevant variants in specific populations and typical initial manifestations may facilitate early diagnosis and treatment. We here describe the genetic landscape of ATTRv amyloidosis in Israel.

METHODS

Genetic and clinical data of TTR variant carriers and ATTRv amyloidosis patients were collected from a national referral clinic and other subspecialty clinics in Israel. Genotype-phenotype correlations of the detected variants were detailed. In addition, two large Israeli exome sequence (ES) databases were screened for TTR variants.

RESULTS

Seven heterozygous disease-causing variants in TTR were identified among 95 adults (52 males, 50.7%). The Ser77Tyr variant was found in 68 (71.6%) subjects of Jewish Yemenite ancestry. Val122Ile was found in 9 (9.4%) subjects and was the only variant detected in individuals of Arab ethnicity. Other variants were Thr60Ala, Val30Met, Val32Ala, Ala81Val, and Glu89Val. Thirty-five individuals were ATTRv amyloidosis patients (25 males, 71.4%), diagnosed at a mean age of 62.5 ± 6.7 years, and 23 (63.7%) were due to Ser77Tyr. Initial symptoms were mostly related to carpal tunnel syndrome, and the sensitivity of scintigraphy was low for Ser77Tyr but high for Thr60Ala and Val32Ala variants. TTR pathogenic variants were detected in 14 of approximately 36,600 subjects who underwent ES, including Val122Ile in 9 subjects of Arab ethnicity.

CONCLUSIONS

Most ATTRv amyloidosis cases in Israel are attributable to the Ser77Tyr variant. However, other variants also contribute to disease occurrence, and testing is warranted in clinically suspected patients.

A phenotypic comparison of the Romanian and French ATTRv cohorts: Glu54Gln founder pathogenic variant vs the most common variants in Western Europe

AIM AND METHODS

We conducted a retrospective observational study of the ATTRv heterozygous mutation frequency, phenotype, and all-cause mortality at two cardiac amyloidosis centers in Romania and France.

RESULTS

291 patients were included: 26 Glu54Gln (all Romanian), 200 Val122Ile, 47 Val30Met and 18 Ser77Tyr. On diagnosis, Gu54Gln patients were younger than Val122Ile or late-onset Val30Met (median age: 46 [42-50], 76 [71-80] and 70 [61-76], respectively; p < 0.001) and had more autonomic dysfunction (50 %, 6.3 %, and 7.7 %, respectively; p < 0.001) and similar cardiac symptom profiles. They had fewer conduction disorders (11.5 %) than early-onset Val30Met (76.9 %, p < 0.001) and Ser77Tyr group, notably less cardiac pacemaker present on diagnosis: 3.8 % for Glu54Gln vs. 23.5 % for Ser77Tyr; p = 0.014. Glu54Gln, Val122Ile, late-onset Val30Met and Ser77Tyr patients had similar left ventricular mass and systolic function values. Median survival for Glu54Gln patients was 58.7 years (95 %CI 55.9 - upper bound indeterminable), significantly lower than that of Val122Ile (83.6 years 95 %CI 81.6-85.5, log-rank test p < 0.001), late-onset Val30Met (83.4 years 95 %CI 81.9-84.9, log-rank test p < 0.001) and Ser77Tyr (74.8 years 95 %CI 68.7-80.9, log-rank test p = 0.022). Median survival after diagnosis was 5.7 years for Glu54Gln patients (95 %CI 4.7-6.4).

CONCLUSION

We established that the Glu54Gln variant has an aggressive, mixed phenotype, with an early onset of autonomic dysfunction and heart failure symptoms. We emphasize the need for systematic genetic testing in patients with ATTR as understanding genotype-phenotype correlations is key for the management and the counseling of patients and their family members.

Clinical and biochemical characterization of asymptomatic carriers and symptomatic patients with hereditary transthyretin amyloidosis caused by TTR V30L mutation

BACKGROUND

Hereditary transthyretin amyloidosis (ATTR) is an autosomal dominant disease characterized by amyloid fibril deposition. The TTR c.148G > T mutation (V30L) in ATTR is rarely reported, and its biochemical properties are unknown.

METHODS

Seven patients and two asymptomatic carriers from two unrelated families diagnosed with V30L variant of ATTR were included. Data on clinical manifestations, laboratory examination, electrophysiology, ophthalmological corneal confocal microscopy (CCM), pathology and molecular biological experiments was collected and analyzed.

RESULTS

Most patients initially experienced paresthesia, with varying degrees of peripheral neuropathy, autonomic dysfunction, and cardiac involvement. Nerve conduction studies showed extensive motor and sensory nerve involvement in upper and lower limbs. CCM revealed reduced corneal nerve density and fiber length. Sural nerve biopsies indicated loss of myelinated nerve fibers, with neurogenic patterns in gastrocnemius muscle biopsies. Asymptomatic carriers had nearly normal electrophysiology but mild reductions in corneal nerve fiber density and length. Sural nerve biopsies in carriers showed mild reductions in small myelinated nerve fibers. V30L mutation impaired thermodynamic and kinetic stability of the mutant protein. Plasma TTR tetramer concentration was lower in ATTR V30L patients compared to healthy donors. Small molecule stabilizers failed to exhibit satisfactory inhibition on fibril formation of V30L mutation in vitro.

CONCLUSION

This study highlights the multisystem involvement in ATTR V30L patients, including neuropathy and cardiac issues. Both patients and carriers showed abnormalities in nerve conduction, corneal microscopy, and pathology. The V30L mutation impaired protein stability and reduced plasma TTR tetramer levels. Small molecule stabilizers were ineffective, indicating a need for alternative treatments.

Clinical differential factors in patients with hereditary transthyretin amyloidosis with Val142Ile and Ser43Asn mutations

BACKGROUND

Hereditary transthyretin amyloidosis (hATTR) is a rare autosomal dominant disease with high clinical variability, influenced by both genotype and the geographic origins of carriers. There is a limited understanding of the Val142Ile and Ser43Asn recognised mutations in Ecuador and Colombia. Therefore, the objective of this study is to describe the neurological and functional characteristics of patients with hATTR associated with the Val142Ile and Ser43Asn mutations, as well as to identify possible differentiating factors between the two mutations.

METHODS

This cross-sectional, multicenter study included 35 hATTR patients from rehabilitation centers in Ecuador and Colombia. Patients had confirmed Val142Ile or Ser43Asn mutations. Neurological and functional assessments included the Neurological Impairment Scale, Norfolk Quality of Life-Diabetic Neuropathy (QOL-DN), Composite Autonomic Symptom Score-31, and various motor function tests as nine-hole peg test (NHP). Quantitative Sensory Testing (QST) evaluating small fiber function, while ultrasound measured the cross-sectional area (CSA) of peripheral nerves. Statistical analysis employed nonparametric tests and random forest classifiers, using SHAP values to identify differentiating variables.

RESULTS

Val142Ile carriers showed lower performance in the right NHP test and greater sensitivity to cold pain in hand and leg. Ultrasound revealed increased CSA of the median nerve at the elbow and arm and the ulnar nerve at the arm in Val142Ile carriers compared to Ser43Asn carriers. The final random forest model identified the NHP test, Norfolk QOL-DN score, and CSA of the median and ulnar nerves as key discriminating variables.

CONCLUSION

This study identified significant neurophysiological and ultrasound markers differentiating Val142Ile and Ser43Asn mutations in hATTR-PN patients. Increased nerve CSA and specific motor and sensory impairments highlight the need for comprehensive evaluations to guide diagnosis and treatment.

Amyloidosis in Childhood: A Review of Clinical Features and Comparison with Adult Forms

Amyloidosis is a rare multisystem disorder characterized by extracellular accumulation of insoluble fibrils in various organs and tissues. The most common subtype in the pediatric population is systemic reactive amyloidosis, typically developing secondary to chronic inflammatory conditions and resulting in deposition of serum amyloid A protein in association with apolipoprotein HDL3. Clinical presentation is highly variable and is mostly influenced by specific organs involved, precursor protein type, and extent of amyloid deposition, often closely reflecting clinical features of the underlying disease. The most critical determinants of prognosis are cardiac and renal involvement. Diagnosis of amyloidosis is confirmed by tissue biopsy, which remains the gold standard, followed by precise amyloid fibril typing. The primary therapeutic approach is directed towards controlling underlying disease and reducing serum levels of precursor proteins to prevent further amyloid deposition. This study aims to highlight the main clinical characteristics of amyloidosis with onset in childhood, emphasizing the key differences compared to adult form.

Neuroprotective effect against amyloidogenic transthyretin aggregates - Induced cytotoxicity on human neuroblastoma cell by phenolic-rich Centella asiatica extract

Transthyretin (ATTR) amyloidosis is a progressive and life-threatening neurodegenerative disease caused by aggregation of the plasma transport protein, transthyretin, for which treatment is rare and cure unavailable. Centella asiatica is a small edible herb with a long history of neurological application in ethnomedicine. This work investigated whether hydrophilic extract of C. asiatica (CAB) could suppress the toxic effects of transthyretin amyloid aggregate (TTRa) in cell model derived from the same in vivo target. TTRa was prepared via thermal-induced aggregation. Chemical cross-linking and Tricine-SDS-PAGE, Thioflavin-T fluorescence, and TEM analyses confirmed that TTRa matched the profile of TTRL55P nonfibrillar amyloid aggregates. PrestoBlue cell viability assay revealed that exposure of IMR-32 human neuroblastoma cells to TTRa (2-8 μM) resulted in significant cytotoxicity. Conversely, exposure of IMR-32 cells to CAB did not adversely affect their viability. In addition, when IMR-32 cells were co-treated with TTRa and varied concentrations of CAB, the toxic effect of TTRa was significantly (p < 0.01) inhibited dose-dependently. The extract was found to possess potent radical scavenging effects, and quantitative RP-HPLC analysis showed that asiaticoside and phenolics were its main components. The cytoprotective effect against TTRa, antioxidant property, and good safety profile collectively suggest that CAB could be applied in the development of nutraceuticals or therapeutics against transthyretin amyloidosis.

Transthyretin amyloid polyneuropathy in France: A cross-sectional study with 413 patients and real-world tafamidis meglumine use (2009-2019)

OBJECTIVE

We aimed to describe characteristics of patients with ATTR variant polyneuropathy (ATTRv-PN) and ATTRv-mixed and assess the real-world use and safety profile of tafamidis meglumine 20mg.

METHODS

Thirty-eight French hospitals were invited. Patient files were reviewed to identify clinical manifestations, diagnostic methods, and treatment compliance.

RESULTS

Four hundred and thirteen patients (296 ATTRv-PN, 117 ATTRv-mixed) were analyzed. Patients were predominantly male (68.0%) with a mean age of 57.2±17.2 years. Interval between first symptom(s) and diagnosis was 3.4±4.3 years. First symptoms included sensory complaints (85.9%), dysautonomia (38.5%), motor deficits (26.4%), carpal tunnel syndrome (31.5%), shortness of breath (13.3%), and unexplained weight loss (16.0%). Mini-invasive accessory salivary gland or punch skin and nerve biopsies were most common, with a performance of 78.8-100%. TTR genetic sequencing, performed in all patients, revealed 31 TTR variants. Tafamidis meglumine was initiated in 156/214 (72.9%) ATTRv-PN patients at an early disease stage. Median treatment duration was 6.00 years in ATTRv-PN and 3.42 years in ATTRv-mixed patients. Tafamidis was well tolerated, with 20 adverse events likely related to study drug among the 336 patients.

CONCLUSION

In France, ATTRv patients are usually identified early thanks to the national network and the help of diagnosis combining genetic testing and mini-invasive biopsies.

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.

"Living with a question mark": psychosocial experience of Portuguese young adults at risk for hereditary amyloid transthyretin amyloidosis with polyneuropathy

This study is the first to explore the psychosocial experience of young Portuguese adults at genetic risk for hereditary amyloid transthyretin amyloidosis with polyneuropathy (hATTR-PN). The work focuses on the developmental peculiarities of their experience with the disease. Sixteen semi-structured interviews were conducted with young adults coming for pre-symptomatic testing (PST) at a single genetics outpatient center in Portugal. The data were analyzed qualitatively. The main findings suggest that four themes mark the psychosocial experience of the young adults interviewed. The first refers to the development of psychological representations, namely beliefs, mental representations, and social perceptions about hATTR-PN. The second regards the experienced and anticipated psychosocial impacts, namely, suffering, anxiety, and relief related to the disease. The third is related to using strategies such as performing PST, strategies focused on emotional regulation and the meaning of hATTR-PN, and social strategies to deal with these impacts over time. Finally, the fourth aspect concerns the perceived and expected support for the participants' needs provided by social contexts, that is, family and genetic counseling. In a period of life also marked by qualitatively different characteristics and developmental tasks from other life cycle stages (e.g., identity explorations, instability, and independent decision-making), experience with the disease can add psychosocial challenges to young adults at risk for hATTR-PN. Genetic counseling practices and health policies can be optimized to respond to the psychosocial needs of young adults. Future research should deepen the understanding of the psychosocial experience of individuals and families with late-onset hATTR-PN to improve the clinical response in this population.

Islands and Neurology: An Exploration into a Unique Association

The current study investigates the intricate connection between neurology and islands shedding light on the historical, epidemiological, and genetic aspects. Based on an elaborate literature review, we identified neurological conditions having a significant clustering in an island(s), confined to a particular island(s), named after an island, and described first in an island. The genetic factors played a crucial role, uncovering disorders like Cayman ataxia, Machado Joseph disease, SGCE-mediated dystonia-myoclonus syndrome, X-linked dystonia parkinsonism, hereditary transthyretinrelated amyloidosis, Charcot Marie Tooth 4F, and progressive myoclonic epilepsy syndromes, that exhibited remarkable clustering in diverse islands. Local customs also left enduring imprints. Practices such as cannibalism in Papua New Guinea led to Kuru, while cycad seed consumption in Guam triggered Lytico-Bodig disease. Toxin-mediated neurologic disorders exhibited intricate island connections, exemplified by Minamata disease in Kyushu islands and atypical parkinsonism in French Caribbean islands. Additionally, the Cuban epidemic of amblyopia and neuropathy was associated with severe nutritional deficiencies. This study pioneers a comprehensive review narrating the genetic, environmental, and cultural factors highlighting the spectrum of neurological disorders in island settings. It enriches the medical literature with a unique understanding of the diverse influences shaping neurological health in island environments.

Identification and management of gastrointestinal manifestations of hereditary transthyretin amyloidosis: Recommendations from an Italian group of experts

Gastrointestinal manifestations are common across all hereditary transthyretin amyloidosis (ATTRv) genotypes. However, they are poorly specific, and their recognition as part of ATTRv is difficult, resulting in misdiagnosis with more common conditions. Moreover, delays in diagnosis occur because of fragmented knowledge, a shortage of centers of excellence and specialists dedicated to ATTRv management, and the scarce involvement of gastroenterologists in multidisciplinary teams. A group of Italian gastroenterologists with experience in the management of ATTRv took part in a project aimed at assessing the awareness of ATTRv among the community of Italian gastroenterologists through an online survey and providing education about practical aspects of ATTRv management. Survey results reported low participation, and very few patients with ATTRv were cared for by gastroenterologists. This highlights the need for greater attention to rare diseases in gastroenterology and emphasizes increasing awareness of ATTRv and diagnostic suspicion. Based on the experts' recommendations, a diagnosis of ATTRv should be suspected when at least one of the 'red flags' is detected. Subsequently, it is suggested to promptly ask for genetic testing and exclude a serum and urinary monoclonal protein, even before the detection of amyloid in biopsy samples, particularly in non-endemic areas.

Clinical spectrum of Transthyretin amyloidogenic mutations among diverse population origins

PURPOSE

Coding mutations in the Transthyretin (TTR) gene cause a hereditary form of amyloidosis characterized by a complex genotype-phenotype correlation with limited information regarding differences among worldwide populations.

METHODS

We compared 676 diverse individuals carrying TTR amyloidogenic mutations (rs138065384, Phe44Leu; rs730881165, Ala81Thr; rs121918074, His90Asn; rs76992529, Val122Ile) to 12,430 non-carriers matched by age, sex, and genetically-inferred ancestry to assess their clinical presentations across 1,693 outcomes derived from electronic health records in UK biobank.

RESULTS

In individuals of African descent (AFR), Val122Ile mutation was linked to multiple outcomes related to the circulatory system (fold-enrichment = 2.96, p = 0.002) with the strongest associations being cardiac congenital anomalies (phecode 747.1, p = 0.003), endocarditis (phecode 420.3, p = 0.006), and cardiomyopathy (phecode 425, p = 0.007). In individuals of Central-South Asian descent (CSA), His90Asn mutation was associated with dermatologic outcomes (fold-enrichment = 28, p = 0.001). The same TTR mutation was linked to neoplasms in European-descent individuals (EUR, fold-enrichment = 3.09, p = 0.003). In EUR, Ala81Thr showed multiple associations with respiratory outcomes related (fold-enrichment = 3.61, p = 0.002), but the strongest association was with atrioventricular block (phecode 426.2, p = 2.81 × 10- 4). Additionally, the same mutation in East Asians (EAS) showed associations with endocrine-metabolic traits (fold-enrichment = 4.47, p = 0.003). In the cross-ancestry meta-analysis, Val122Ile mutation was associated with peripheral nerve disorders (phecode 351, p = 0.004) in addition to cardiac congenital anomalies (fold-enrichment = 6.94, p = 0.003).

CONCLUSIONS

Overall, these findings highlight that TTR amyloidogenic mutations present ancestry-specific and ancestry-convergent associations related to a range of health domains. This supports the need to increase awareness regarding the range of outcomes associated with TTR mutations across worldwide populations to reduce misdiagnosis and delayed diagnosis of TTR-related amyloidosis.

Diagnosis and treatment of hereditary transthyretin amyloidosis with polyneuropathy in the United States: Recommendations from a panel of experts

Hereditary transthyretin (ATTRv; v for variant) amyloidosis is a rare, multisystem, progressive, and fatal disease in which polyneuropathy is a cardinal manifestation. Due to a lack of United States (US)-specific guidance on ATTRv amyloidosis with polyneuropathy, a panel of US-based expert clinicians convened to address identification, monitoring, and treatment of this disease. ATTRv amyloidosis with polyneuropathy should be suspected in unexplained progressive neuropathy, especially if associated with systemic symptoms or family history. The diagnosis is confirmed through genetic testing, biopsy, or cardiac technetium-based scintigraphy. Treatment should be initiated as soon as possible after diagnosis, with gene-silencing therapeutics recommended as a first-line option. Consensus is lacking on what represents "disease progression" during treatment; however, the aggressive natural history of this disease should be considered when evaluating the effectiveness of any therapy.

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.

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

BACKGROUND

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

OBJECTIVES

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

DESIGN

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

PARTICIPANTS

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

MAIN OUTCOME MEASURE

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

RESULTS

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

CONCLUSIONS

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

A multicentric study of the disease risks and first manifestations in hereditary transthyretin amyloidosis (ATTRv): insights for an earlier diagnosis

BACKGROUND

In hereditary transthyretin amyloidosis (ATTRv), early manifestation and age at onset (AO) may vary strikingly. We assessed the disease'risk (penetrance), AO and initial features in ATTRv families to gain insights on the early disease presentation.

METHODS

Genealogical information, AO and first disease manifestations were collected in ATTRv families, from Sweden, Italy (Sicily), Spain (Mallorca), France, Turkey, Brazil. Penetrance was computed using a non-parametric survival method.

RESULTS

We analysed 258 TTRV30M kindreds and 84 carrying six other variants (TTRT49A, F64L, S77Y, S77F, E89Q, I107V). In ATTRV30M families, the earliest disease risk was found at age 20 years in the Portuguese and Mallorcan families and at age 30-35 years, in the French and Swedish groups. The risks were higher in men and in carriers of maternal descent. In families carrying TTR-nonV30M variants, the earliest disease risk ranged from 30 y-o in TTRT49A to 55 y-o in TTRI107V families. Peripheral neuropathy symptoms were the most frequent initial manifestations. Among patients carrying TTRnonV30M variants, about 25% had an initial cardiac phenotype, one third a mixed phenotype.

CONCLUSION

Our work provided solid data on the risks and early features of ATTRv in a spectrum of families to enhance an early diagnosis and 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.

Clinical model for Hereditary Transthyretin Amyloidosis age of onset prediction

Introduction

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

Materials and methods

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

Results

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

Discussion

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Functional and morphometric assessment of small-fibre damage in late-onset hereditary transthyretin amyloidosis with polyneuropathy: the controversial relation between small-fibre-related symptoms and diagnostic test findings

INTRODUCTION

We aimed at investigating whether functional and morphometric tests assessing small-fibre damage, ie quantitative sensory testing, Sudoscan and skin biopsy, reliably reflect neuropathic pain and autonomic symptoms in patients with late-onset hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN).

METHODS

In 30 patients with late-onset ATTRv-PN, we collected quantitative sensory testing, Sudoscan and skin biopsy with assessment of intraepidermal, piloerector muscle and sweat gland nerve fibre density. We then correlated these functional and morphometric parameters with neuropathic pain and autonomic symptoms as assessed with the Neuropathic Pain Symptom Inventory (NPSI) and Composite Autonomic Symptom Score-31 (COMPASS-31).

RESULTS

50% of patients showed small-fibre damage in the form of a pure small-fibre neuropathy, 47% in the context of a mixed fibre neuropathy with small and large fibre involvement. All patients complained of at least one autonomic symptom and 60% had neuropathic pain. Whereas quantitative sensory testing and Sudoscan parameters correlated with neuropathic pain and autonomic symptoms as assessed by NPSI and COMPASS-31, intraepidermal, piloerector muscle and sweat gland nerve fibre density quantification did not.

CONCLUSIONS

Our findings indicate that functional test parameters reliably reflect neuropathic pain and autonomic symptoms related to small-fibre damage. These findings might help to identify clinically useful biomarkers to assess patient follow-up.

Cardiac Amyloidosis

Amyloidosis is a pathologic and clinical condition resulting from the accumulation of insoluble aggregates of misfolded proteins in tissues. Extracellular deposition of amyloid fibrils in the myocardium leads to cardiac amyloidosis, which is often overlooked as a cause of diastolic heart failure. Although cardiac amyloidosis was previously believed to have a poor prognosis, recent advances in diagnosis and treatment have emphasized the importance of early recognition and changed management of this condition. This article provides an overview of cardiac amyloidosis and summarizes current screening, diagnosis, evaluation, and treatment options.

A retrospective survey of patients with hereditary transthyretin-mediated (hATTR) amyloidosis treated with patisiran in real-world clinical practice in Belgium

INTRODUCTION

Hereditary transthyretin-mediated (hATTR) amyloidosis, a genetic disease caused by mutations in the transthyretin gene, leads to progressive sensory and autonomic neuropathy and/or cardiomyopathy and is associated with renal and ophthalmologic manifestations and a poor prognosis.

METHODS

This is a retrospective study based on data collected from the medical records of patients with hATTR amyloidosis treated with patisiran between 01 July 2018 and 01 February 2021. Six Belgian neuromuscular reference centers participated, covering all patisiran-treated hATTR amyloidosis patients at the study time. This study was conducted to collect data requested in the context of the reimbursement of patisiran in Belgium.

RESULTS

Thirty-one patients were diagnosed with hATTR amyloidosis with polyneuropathy, Coutinho stage 1 or 2, and eligible for active treatment during the data collection period. Of the hATTR amyloidosis patients treated with patisiran (n = 12), seven and five had polyneuropathy stages 1 and 2, respectively. Six patients had cardiac symptoms (New York Heart Association class 2 or above). Follow-up information was available for nine patients. Following patisiran treatment, eight patients showed stable or improved assessments for most neurological or cardiological parameters. Only one patient presented with worsening statuses at the end of the data collection period.

CONCLUSIONS

The patients with hATTR amyloidosis in Belgium have similar baseline demographics and disease characteristics to those studied in the patisiran APOLLO study and show a similar therapeutic response in the real-world, altering the expected disease progression in most patients.

Updated Evaluation of the Safety, Efficacy and Tolerability of Tafamidis in the Treatment of Hereditary Transthyretin Amyloid Polyneuropathy

Hereditary amyloid transthyretin (ATTRv) amyloidosis is a devastating hereditary multisystemic disease affecting predominantly the peripheral and autonomic nervous systems and the heart. ATTRv is caused by mutations in the transthyretin (TTR) gene, leading to extracellular deposition of amyloid fibrils in multiple organs including the peripheral nervous system. If untreated, it is associated with a fatal outcome 10-12 years after disease onset. Different treatments are available for patients with ATTRv polyneuropathy. Tafamidis 20 mg is approved in Europe since 2011 for early stages of ATTRv polyneuropathy (stage I - able to walk without support) and it is recommended as first-line therapy in these patients. Tafamidis is a TTR stabilizer that selectively binds to TTR and kinetically stabilizes both wild-type native TTR and mutant TTR. Consequently, it has the potential to prevent the amyloidogenic cascade initiated by TTR tetramer dissociation into its monomers and subsequent misfolding and aggregation. Tafamidis is an oral drug, taken once per day, with proved efficacy, safety and tolerability in ATTRv-PN patients as demonstrated in different clinical trials and open-label extension studies as well in clinical practice setting with around 10 years of experience. Tafamidis treatment started in the earliest stages of the disease is associated with better neurological outcomes. A multidisciplinary approach in referral centres is also fundamental for monitoring patients to assess individual response to treatment.

Ser77Tyr transthyretin amyloidosis in Israel: Initial manifestations and diagnostic features

OBJECTIVE

Amyloidosis due to the transthyretin Ser77Tyr mutation (ATTRS77Y) is a rare autosomal-dominant disorder, characterized by carpal-tunnel syndrome, poly- and autonomic-neuropathy, and cardiomyopathy. However, related symptoms and signs are often nonspecific and confirmatory tests are required. We describe the age and frequency of early symptoms and diagnostic features among individuals of Jewish Yemenite descent in Israel.

METHODS

Records of mutation carriers were retrospectively reviewed. ATTRS77Y diagnosis was defined by the presence of amyloid in tissue and/or amyloid-related cardiomyopathy.

RESULTS

We identified the Ser77Tyr mutation at the heterozygous state in 19 amyloidosis patients (mean age at diagnosis: 62 ± 5.7 years, range 49-70) and 30 amyloid-negative carriers. The probability for disease diagnosis increased from 4.4% at age 49 to 100% at 70 and occurred earlier in males. Initial symptoms preceded diagnosis by 5 ± 3.8 years (range 0-12) and were commonly sensory changes in the extremities. Erectile dysfunction predated these in 8/13 (62%) males. In two patients cardiac preceded neurological symptoms. Two patients declined symptoms. Electrophysiological studies near the time of diagnosis indicated a median neuropathy at the wrist in 18/19 (95%) and polyneuropathy in 13/19 (68%). Skin biopsy revealed epidermal denervation in 15/16 (94%) patients. Cardiomyopathy was identified in 16/19 (84%). Sensory complaints or epidermal denervations were present in 17/30 (57%) of amyloid-negative carriers and co-occurred in 10/30 (33%).

INTERPRETATION

ATTRS77Y symptoms commonly occur after age 50, but may begin earlier. Median neuropathy, skin denervation and cardiomyopathy are frequently identified. Symptoms may be absent in patients and common in amyloid-negative carriers.

Does [99mTc]-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) soft tissue uptake allow the identification of patients with the diagnosis of cardiac transthyretin-related (ATTR) amyloidosis with higher risk for polyneuropathy?

BACKGROUND

With the introduction of several drugs for the therapy of transthyretin-related amyloidosis (ATTR) which slow down the disease, early detection of polyneuropathy (PNP) is becoming increasingly of interest. [99mTc]-3,3-Diphosphono-1,2-Propanodicarboxylic Acid (DPD) bone scintigraphy, which is used for the diagnosis of cardiac (c)ATTR, can possibly make an important contribution in the identification of patients at risk for PNP.

METHODS

Fifty patients with cATTR, who underwent both planar whole-body DPD scintigraphy and nerve conduction studies (NCS) were retrospectively evaluated. A subgroup of 22 patients also underwent quantitative SPECT/CT of the thorax from which Standardized Uptake Values (SUVpeak) in the subcutaneous fat tissue of the left axillar region were evaluated.

RESULTS

The Perugini score was significantly increased in patients with cATTR and additional diagnosis of PNP compared to patients without (2.51 ± 0.51 vs 2.13 ± 0.52; P = 0.03). Quantitative SPECT/CT revealed that DPD uptake in the subcutaneous fat of the left axillar region was significantly increased in cATTR patients with compared to patients without (1.36 ± 0.60 vs 0.74 ± 0.52; P = 0.04).

CONCLUSION

This study suggests that DPD bone scintigraphy is a useful tool for identification of patients with cATTR and a risk for PNP due to increased DPD soft tissue uptake.

A survey exploring caregiver burden and health-related quality of life in hereditary transthyretin amyloidosis

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv) is an ultra-rare, life-shortening disease with a high unmet need. This study examined ATTRv caregiver health-related quality of life (HRQoL) and productivity.

METHODS

A cross-sectional online survey, including EQ-5D-3L, Hospital anxiety and depression scale (HADS), and caregiver and patient characteristics questions, was developed to assess ATTRv caregiver burden. A companion general population survey collected EQ-5D-3L, HADS and chronic health conditions data. Caregiver-control group differences in HRQoL were assessed using t-tests and chi-square tests. Ordinary Least Squares regression was used to estimate the disutility of being a caregiver compared to controls stratified by patient ambulatory status.

RESULTS

Thirty-six caregivers and matched controls completed the survey (n = 72). The disease severity of patients they cared for was varied: 33% required no assistance walking, 58% required assistance with walking and 9% required a wheelchair/were bedridden. On average, caregivers spent 6 h daily on practical care and 4 h daily on emotional support. Fifty-six percent indicated that they had changed their employment due to providing ATTRv care. Caregivers reported lower HRQoL, as indicated by lower EQ-5D 3L utility scores (M = 0.772, SD = 0.178 vs. M = 0.849, SD = 0.218) and higher HADS anxiety (9.3 vs. 6.1, p < 0.01) and depression (7.6 vs. 4.4, p < 0.01) scores, compared with matched controls. Caregivers were also more likely to report sleep problems (33% vs. 8%, p < 0.01) and stress (42% vs. 0%, p < 0.001) as chronic conditions than controls.

CONCLUSIONS

The study results indicate that caring for a person with ATTRv can have a considerable negative impact on caregivers' HRQoL and productivity. The study findings provide important information for economic evaluations of ATTRv treatments.

Leptomeningeal Disease Secondary to Thr60Ala Transthyretin Amyloidosis: Case Report and Review of the Literature

A 31-year-old woman with transthyretin (TTR) amyloidosis secondary to a Thr60Ala mutation developed recurrent stroke-like episodes with fluctuating mental status. Evaluation for stroke and seizures was unrevealing. She was found to have leptomeningeal contrast enhancement on magnetic resonance imaging, which was confirmed to be CNS TTR amyloidosis on histopathology following brain and dura biopsy. While leptomeningeal disease has rarely been known to be associated with TTR amyloidosis, this is the first documented case of leptomeningeal disease secondary to a Thr60Ala mutation in the TTR gene. A literature review of TTR amyloidosis is presented with special focus on the treatment of leptomeningeal TTR amyloidosis.

Hereditary transthyretin amyloidosis overview

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

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

BACKGROUND

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

METHODS

The Transthyretin Amyloidosis Outcomes Survey (THAOS) is an ongoing, global, longitudinal, observational survey of patients with transthyretin amyloidosis, including both inherited and wild-type disease, and asymptomatic TTR gene carriers. Asymptomatic TTR gene carriers were assessed longitudinally to identify those who developed ATTRv amyloidosis after enrolment in THAOS (data cut-off: 1 August 2021).

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00628745.

Hereditary transthyretin amyloidosis in Sweden: Comparisons between a non-endemic and an endemic region

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv) is endemic in northern Sweden (Västerbotten). The awareness of ATTRv amyloidosis is lower in Stockholm, a non-endemic region in Sweden. The aim of this study was to compare the possible differences in diagnostic delay, disease phenotypes, treatment and survival between a non-endemic and an endemic region in Sweden.

METHODS

The in- and outpatient diagnosis registry at the Department of Neurology at Karolinska University Hospital and the Amyloidosis Centre at University Hospital of Umeå were used to identify patients between January 2006 and November 2017.

RESULTS

In total, 21 patients in Stockholm and 134 patients in Västerbotten were included. The time between symptom onset to time-point of diagnosis was significantly longer in Stockholm vs Västerbotten. This corresponded to a longer median time between first visit at amyloidosis centre to time-point of diagnosis in Stockholm vs in Västerbotten. The most common reason for a diagnostic delay was negative tissue biopsies.

CONCLUSION

There was a diagnostic-, but no patient-delay in non-endemic Stockholm vs endemic Västerbotten. Despite a more severe neuropathic phenotype in Stockholm at the onset, the systemic affection over the course of disease and of survival seems not to be influenced by the diagnosis delay in Stockholm.

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.

Hereditary Transthyretin-Related Amyloidosis: Genetic Heterogeneity and Early Personalized Gene Therapy

Point mutations of the transthyretin (TTR) gene are related with hereditary amyloidosis (hATTR). The number of people affected by this rare disease is only partially estimated. The real impact of somatic mosaicism and other genetic factors on expressivity, complexity, progression, and transmission of the disease should be better investigated. The relevance of this rare disease is increasing and many efforts have been made to improve the time to diagnosis and to estimate the real number of cases in endemic and non-endemic areas. In this context, somatic mosaicism should be better investigated to explain the complexity of the heterogeneity of the hATTR clinical features, to better estimate the number of new cases, and to focus on early and personalized gene therapy. Gene therapy can potentially improve the living conditions of affected individuals and is one of the central goals in research on amyloidosis related to the TTR gene, with the advantage of overcoming liver transplantation as the sole treatment for hATTR disease.

Gait Characterization and Analysis of Hereditary Amyloidosis Associated with Transthyretin Patients: A Case Series

Hereditary amyloidosis associated with transthyretin (ATTRv), is a rare autosomal dominant disease characterized by length-dependent symmetric polyneuropathy that has gait impairment as one of its consequences. The gait pattern of V30M ATTRv amyloidosis patients has been described as similar to that of diabetic neuropathy, associated with steppage, but has never been quantitatively characterized. In this study we aim to characterize the gait pattern of patients with V30M ATTRv amyloidosis, thus providing information for a better understanding and potential for supporting diagnosis and disease progression evaluation. We present a case series in which we conducted two gait analyses, 18 months apart, of five V30M ATTRv amyloidosis patients using a 12-camera, marker based, optical system as well as six force platforms. Linear kinematics, ground reaction forces, and angular kinematics results are analyzed for all patients. All patients, except one, showed a delayed toe-off in the second assessment, as well as excessive pelvic rotation, hip extension and external transverse rotation and knee flexion (in stance and swing phases), along with reduced vertical and mediolateral ground reaction forces. The described gait anomalies are not clinically quantified; thus, gait analysis may contribute to the assessment of possible disease progression along with the clinical evaluation.

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

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

Kidney involvement in hereditary transthyretin amyloidosis: a cohort study of 103 patients

Background

Hereditary transthyretin amyloidosis (ATTRv) is a disabling and life-threatening disease that primarily affects the nervous system and heart. Its kidney involvement has not been systematically studied, particularly in non-V30M mutations, and is not well known to nephrologists.

Methods

We conducted a retrospective study describing the kidney phenotype of all prevalent patients with ATTR mutations, with neurological or cardiac involvement or presymptomatic carriers, followed up in two university hospitals from the South of France between June 2011 and June 2021.

Results

A total of 103 patients were included, among whom 79 were symptomatic and 24 were presymptomatic carriers. Patients carried 21 different ATTR mutations and 54% carried the V30M mutation. After a mean follow-up of 7.9 ± 25.7 years, 30.4% of the symptomatic patients had developed chronic kidney disease (CKD) and 20.3% had a urinary protein:creatinine ratio ≥0.5 g/g. None of the presymptomatic carriers had CKD or proteinuria. In a multivariate analysis, late onset of symptoms (after 60 years), the V122I mutation and proteinuria were significantly associated with CKD. The median CKD-free survival in symptomatic patients was estimated at 81.0 years (interquartile range 77.1–84.9). It did not differ between V30M and non-V30M patients, but was lower in patients with the V122I mutation. The average age of the onset of CKD was 69.3 ± 13.0 years. In one 38-year-old V30M female who presented a kidney-predominant phenotype, treatment with patisiran resulted in remission of the nephrotic syndrome.

Conclusion

CKD affects almost one-third of patients with symptomatic ATTRv. The role of ATTRv per se in the development of CKD in this population remains to be determined, but some patients may benefit from specific therapies.

[Gene therapy options for hereditary transthyretin-related amyloidosis]

Hereditary transthyretin-related amyloidosis (ATTRv) is a rare autosomal dominant disease and is fatal if left untreated. It is caused by mutations in the transthyretin gene. All known mutations induce misfolding of the tetrameric transthyretin molecule and protein deposits in multiple organs. In peripheral nerves this result in sensorimotor and autonomic polyneuropathy and in cardiac muscle it causes cardiomyopathy. Untreated ATTRv is characterized by an irreversible and progressive course and death 7-11 years after symptom onset. Treatment options consist of TTR stabilizing drugs, such as tafamidis and active agents that selectively interfere at the mRNA level, the so-called gene silencers patisiran and inotersen. All forms of treatment aim to prevent amyloid tissue deposition in tissues and organ dysfunction. Patisiran works by RNA interference on endogenous mechanisms of gene expression. It results in the cleavage of TTR-mRNA using the cytoplasmatic RNA-induced silencing complex. Inotersen, an antisense oligonucleotide, degrades TTR-mRNA via activation of nuclear RNase H. Both mechanisms result in a significant reduction of TTR protein serum levels. The efficacy could be demonstrated by slowing or improving neuropathy progression in the phase III study APOLLO (patisiran) or the NEURO-TTR study (inotersen). Furthermore, the use of both agents led to an improvement in the quality of life in patients with ATTRv. Both forms of treatment are approved in Germany since August 2018 for polyneuropathy stages 1 and 2 according to Coutinho. The choice of treatment should be carried out individually considering drug formulation, contraindications and the necessary safety monitoring controls.

Seven Years of Selective Genetic Screening Program and Follow-Up of Asymptomatic Carriers With Hereditary Transthyretin Amyloidosis in Bulgaria

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is a rare, autosomal-dominant (AD) multisystem disorder resulting from the extracellular deposition of amyloid fibrils formed by a destabilized mutant form of transthyretin (TTR), a transport protein predominantly produced by the liver.

Transthyretin cardiac amyloidosis in continental Western Europe: an insight through the Transthyretin Amyloidosis Outcomes Survey (THAOS)

AIMS

Transthyretin amyloidosis (ATTR amyloidosis) is a heterogeneous disorder with cardiac, neurologic, and mixed phenotypes. We describe the phenotypic and genotypic profiles of this disease in continental Western Europe as it appears from the Transthyretin Amyloidosis Survey (THAOS).

METHODS AND RESULTS

THAOS is an ongoing, worldwide, longitudinal, observational survey established to study differences in presentation, diagnosis, and natural history in ATTR amyloidosis subjects. At data cut-off, 1411 symptomatic subjects from nine continental Western European countries were enrolled in THAOS [1286 hereditary (ATTRm) amyloidosis; 125 wild-type ATTR (ATTRwt) amyloidosis]. Genotypes and phenotypes varied notably by country. Four mutations (Val122Ile, Leu111Met, Thr60Ala, and Ile68Leu), and ATTRwt, were associated with a mainly cardiac phenotype showing symmetric left ventricular (LV) hypertrophy, normal diastolic LV dimensions and volume, and mildly depressed LV ejection fraction (LVEF). Morphologic and functional abnormalities on echocardiogram were significantly more severe in subjects with cardiac (n'= 210), compared with a mixed (n = 298), phenotype: higher median (Q1-Q3) interventricular septal thickness [18 (16-21) vs. 16 (13-20) mm; P = 0.0006]; and more frequent incidence of LVEF <50% (38.1 vs. 17.5%; P = 0.0008). Subjects with cardiac mutations or ATTRwt (or cardiac or mixed phenotype) had a lower survival rate than subjects in other genotype (or the neurologic phenotype) categories (P < 0.0001, for both).

CONCLUSION

ATTR amyloidosis genotypes and phenotypes are highly heterogeneous in continental Western Europe. A geographic map of the different disease profiles and awareness that a subset of subjects have a dominant cardiac phenotype, mimicking hypertrophic cardiomyopathy, at presentation can facilitate the clinical recognition of this underdiagnosed disease.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00628745.

Determination of Tafamidis Plasma Concentrations in Amyloidosis Patients with Glu89Gln Mutation by HPLC-UV Detection

Present study describes a high-performance liquid chromatography method for the determination of the potent kinetic stabilizer-Tafamidis in human plasma. It was approved for medical use in European Union in 2011. Ultra violet (UV) detection mode and isocratic elution of the mobile phase were set and made the analytical procedure fast and widely applicable. Chromatographic determination was performed on a Purospher® RP-18 column. The mobile phase consisted of 0.1% trifluoroacetic acid in water and acetonitrile in the ratio 42:58 v/v and the flow rate was 1.0 ml/min. All analyses were carried at a room temperature and the detector was set at 280 nm. Calibration curve over a range of 1.00-10.00 μM was constructed for the purposes of linearity method validation. The specificity and effectiveness of the developed method made it suitable for observation of patients' plasma Tafamidis concentration with time and drug therapy monitoring.

Large-scale integration of the plasma proteome with genetics and disease

The plasma proteome can help bridge the gap between the genome and diseases. Here we describe genome-wide association studies (GWASs) of plasma protein levels measured with 4,907 aptamers in 35,559 Icelanders. We found 18,084 associations between sequence variants and levels of proteins in plasma (protein quantitative trait loci; pQTL), of which 19% were with rare variants (minor allele frequency (MAF) < 1%). We tested plasma protein levels for association with 373 diseases and other traits and identified 257,490 associations. We integrated pQTL and genetic associations with diseases and other traits and found that 12% of 45,334 lead associations in the GWAS Catalog are with variants in high linkage disequilibrium with pQTL. We identified 938 genes encoding potential drug targets with variants that influence levels of possible biomarkers. Combining proteomics, genomics and transcriptomics, we provide a valuable resource that can be used to improve understanding of disease pathogenesis and to assist with drug discovery and development.

Hereditary transthyretin-related amyloidosis is frequent in polyneuropathy and cardiomyopathy of no obvious aetiology

BACKGROUND

Hereditary Transthyretin-Related Amyloidosis, a clinically heterogeneous autosomal dominant disease caused by pathogenic variants in the TTR gene, is characterized by the deposition of insoluble misfolded protein fibrils. The diagnosis, especially in non-endemic areas, is typically delayed by 4-5 years; a misdiagnosis due to clinical heterogeneity is common. The study objective was to define the prevalence of Hereditary Transthyretin-Related Amyloidosis in patients with polyneuropathy and/or cardiomyopathy of no obvious aetiology.

METHOD

A multicenter observational "Epidemiological analysis for the hereditary Transthyretin-Related AMyloidosis"-TRAM study was performed in Germany, Austria, and Switzerland.

RESULTS

A total of 5141 participants were recruited by 50 neurologic and 27 cardiologic specialized centres. Genetic analysis demonstrated a 1.1% Hereditary Transthyretin-Related Amyloidosis positivity rate among patients with polyneuropathy and/or cardiomyopathy of not obvious aetiology. Twenty-one various TTR variants (TTR-positive) were identified. Body Mass Index was lower in the TTR-positive patients as an indicator for the involvement of the autonomic nervous system; the age of onset of clinical manifestations was higher in TTR-positive patients. There were no other genotype-phenotype correlations or the prevalence of specific clinical manifestations in TTR-positive patients.

CONCLUSIONS

Our data support the fact that Hereditary Transthyretin-Related Amyloidosis is underdiagnosed in polyneuropathy and cardiomyopathy patients. Routine implementation of genetic testing is recommended in patients with unexplained polyneuropathy and/or cardiomyopathy to accelerate the earlier diagnosis and the time-sensitive treatment initiation.KEY MESSAGESMore than 5.000 participants with CM and/or PNP of no obvious aetiology were recruited in the observational "Epidemiological analysis for the hereditary Transthyretin-Related AMyloidosis" TRAM study and screened for pathogenic TTR variants.The study demonstrated >1% of patients with CM and/or PNP of unclear aetiology are positive for a pathogenic TTR variant.Routine genetic testing is recommended in patients with unexplained CM and/or PNP to accelerate the initial diagnosis and timely treatment initiation.

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.