OBJECTIVE: Systemic amyloidosis is a condition in which misfolded amyloid fibrils are deposited within tissues. Amyloid myopathy is a rare manifestation of systemic amyloidosis. However, whether skeletal muscle involvement is underestimated and whether such deposition guarantees clinical and pathological myopathic features remain to be investigated.
METHODS: We retrospectively reviewed patients with systemic amyloidosis, in whom skeletal muscle biopsies were performed at our centre between January 2018 and June 2023. In total, 28 patients with suspected systemic amyloidosis were included. Among these, 21 presented with cardiomyopathy but lacked myopathic symptoms. The clinical and pathological data of these patients were further analysed. The amyloid type was confirmed by immunohistochemistry.
RESULTS: Twenty-eight patients with suspected systemic amyloidosis underwent muscle biopsy. Amyloid deposition in the skeletal muscle was confirmed in 24 patients, including 22 with light-chain amyloidosis (AL) and two with transthyretin amyloidosis (ATTR). Among the 24 patients, seven presented with muscle weakness and decreased muscle strength (Group 1, symptomatic myopathy), whereas the remaining 17 exhibited normal muscle strength (Group 2, asymptomatic myopathy). Group 1 included four patients with AL-λ, one with AL-κ and two with ATTR. Group 2 included 15 patients with AL-λ and two patients with AL-κ. In Group 1, six patients exhibited neuropathy, whereas only one patient in Group 2 presented with subclinical neuropathy on nerve conduction studies. Amyloid deposition in the interstitium was the most obvious change, observed in all 24 patients. Neuropathic changes, including denervation atrophy and muscle fibre grouping, were also common. Except for type 2 fibre atrophy, the other myopathic changes were mild and nonspecific. No sarcolemmal disruption was observed. Immunohistochemical analysis revealed marked positivity for MAC and MHC1 expression in the regions with amyloid deposits. Clinicopathological analysis revealed no significant differences in the extent of muscular amyloid deposition between the two groups. Nevertheless, patients in Group 1 displayed more pronounced neurogenic atrophy on skeletal muscle biopsies.
CONCLUSIONS: Our study indicates that amyloid deposition in skeletal muscle is commonly observed but rarely causes symptomatic myopathy in systemic amyloidosis.

Transthyretin Amyloidosis arises from the misfolding of monomers or oligomers of the normal transthyretin protein. Our investigation revealed that certain guanine-rich regions within the 5\' UTR sequence of the transthyretin gene possess the ability to form G2-quadruplex structures, as determined through analysis with QGRS mapper. We demonstrated that small molecule ligands, including TMPyP4, Braco-19, NMM, and TO, have a significant impact on the stabilization of transthyretin G-quadruplexes. The objective of this study was to confirm the effect of ligands on transthyretin gene transcription through the stabilization of G-quadruplexes. To comprehend the interaction between ligands and transthyretin G-quadruplexes, a range of analytical techniques were employed, includingUV titration, fluorescence titration assays, circular dichroism, quantitative RT-PCR and cytotoxicity tests. The results revealed the presence of four putative G2-quadruplex sequences, which formed stable anti-parallel, parallel, and hybrid G2-quadruplex structures. Notably, Ttrg 3 (5\'-GGAAGGAAGGGAGGGAGGG-3\') exhibited the highest stability to form G-quadruplex. Furthermore, TmPyP4, Braco-19, NMM and TO were found to stabilize the parallel topology of Ttrg 3. After 48 h of incubation, the RT-PCR experiments revealed a significant reduction in transthyretin mRNA transcription in HepG2 cells when treated with 20 μM TmPyP4 and Braco-19, without inducing apoptosis. Our findings suggested that ligand-mediated stabilization of G-quadruplexes within the 5\'-UTR can effectively silence transthyretin expression, highlighting the potential of G-quadruplex as a novel therapeutic target for Transthyretin Amyloidosis. This study might shed valuable lights for the development of innovative therapeutic approach against Transthyretin Amyloidosis.

Accumulation of aberrant proteins in the heart causes cardiac amyloidosis, an uncommon and complicated illness. It can be classified into two main types: light chain (AL) and transthyretin (ATTR). The diagnosis of cardiac amyloidosis is challenging due to its non-specific clinical presentation and lack of definitive diagnostic tests. Diagnostic accuracy has increased with the advent of modern imaging methods, including cardiac magnetic resonance imaging (MRI) and positron emission tomography (PET) scans. Depending on the severity of cardiac amyloidosis, a number of treatments may be attempted and specified according to the subtype of amyloidosis and the presence of complications. However, there are still significant challenges in treating this condition due to its complexity and lack of effective treatments. The prognosis for patients with cardiac amyloidosis is poor. Despite recent advances in diagnosis and treatment, there is still a need for more effective treatments to improve outcomes for patients with this condition. Therefore, we aim to review the current and future therapeutics reported in the literature and among ongoing clinical trials recruiting patients with CA.

In the new century, cardiac amyloidosis has received more attention from many countries and institutions, leading to innovations in the essence of the pathology, biological markers, noninvasive tests, and staging diagnoses and treatments for this disease. However, few reviews have summarized the research trends and hotspots in cardiac amyloidosis. Bibliometrics analysis is a statistically based approach to research that visualizes the contributions of academic institutions and changes in research hotspots. Therefore, in this paper, we used Citespace and VOSviewer software to conduct co-occurrence analysis and collaborative network analysis on the countries, institutions, and authors in the articles related to cardiac amyloidosis since the new century. And further find out burst keywords and references to obtain the research history, disciplinary development, and new hotspots and topics.

Hereditary transthyretin amyloidosis (hATTR) is a progressive and fatal disease with heterogenous clinical presentations, limited diagnosis and poor prognosis. This retrospective analysis study aimed to report the genotypes and phenotypes of herediary transthyretin amyloidosis (hATTR) in Chinese through a systematic review of published literature.
The systematic review included structured searches of peer-reviewed literature published from 2007 to 2020 of following online reference databases: PubMed, Web of Science and the literature database in China. Extracted data included sample size, personal information (sex, age, natural course, family history), mutation type, clinical milestones and reason of death.
We described 126 Chinese patients with hereditary transthyretin amyloidosis identified through a systematic review of 30 studies. The most common genotype in the Chinese population was Gly83Arg (25, 19.8%), which most likely presented visual and neurological abnormalities without reported death. The second and third most common genotypes were Val30Met (20, 15.9%) and Val30Ala (10, 7.9%). Peripheral neurological manifestations (91, 72%) were dominant in 126 patients. The followed manifestation was autonomic neurological abnormalities (73, 58%). Half of the cases were reported to have visual disorders, and nearly one-third of the cases presented cardiac abnormalities. Among all 126 reported patients, 46.03% were classified as neurological type, 30.16% as mixed type and only 2.38% as cardiac type. In addition. Chinese patients were mostly early onset, with age of onset at 41.8 (SD: 8.9) years, and the median time from onset to death was 7.5 [IQR: 5.3] years. Patients with cardiac involvement had a shorter survival duration (log Rank (Mantel-Cox), χ2 = 26.885, P < 0.001).
This study focused on 126 Chinese hATTR patients obtained from a literature review. A total of 26 kinds of TTR mutations were found and the most common one was Gly83Arg. As for phenotype, 46.03% were classified as neurological type, 30.16% as mixed type and only 2.38% as cardiac type. Chinese hATTR patients were mostly early onset (AO 41.8 years), and the median time from onset to death was 7.5 years.

UNASSIGNED: Hereditary transthyretin amyloid cardiomyopathy (ATTR-CM) is a genotypically heterogeneous disorder with a poor prognosis. There is limited literature describing the variants responsible for ATTRv in areas outside the United State, the United Kingdom and Europe. This study was performed to describe the clinical characteristics and genotypic profiles of this disease in South China.
UNASSIGNED: This was a single-center retrospective study that evaluated 29 patients with a confirmed diagnosis of hereditary transthyretin amyloid cardiomyopathy enrolled from January 2016 to November 2021.
UNASSIGNED: 93.1% patients were male and the median age of symptom onset was 53 (46, 62.5) years old. The initial manifestations of ATTR-CM were cardiovascular symptoms (55.2%), neuropathy (41.4%) and vitreous opacity (3.4%). Phenotypes at diagnosis were mixed (82.8%), predominant cardiac (6.9%), neurological (6.9%) and ophthalmic (3.4%). Poor R-wave progression (41%), pseudo-infarct (31%) and low-voltage (31%) patterns were common findings on electrocardiogram. Unexplained increased wall thickness was observed in all 29 patients, with mean septal and posterior wall thicknesses of 14.25 ± 6.26 mm and 15.34 ± 2.84 mm, respectively. Diastolic dysfunction was also seen in all 29 patients, and 17 (58%) had a restrictive fill pattern at diagnosis. Nine different missense mutations of the TTR gene were found in 29 patients from 23 families, with c.349G>T (p.Ala117Ser) the most common mutation. The median survival time after diagnosis was 47.6 (95% CI 37.9-57.4) months, with 1, 3 and 5-year survival rates of 91.2%, 74% and 38% respectively. Patients with advanced heart failure (National Amyloidosis Staging stage II/III) had worse survival than stage I [Breslow (Generalized Wilcoxon), χ2 = 4.693, P = 0.03)].
UNASSIGNED: ATTR amyloidosis genotypes and phenotypes are highly heterogeneous. Advanced heart failure predicts a poor prognosis. Understanding the different clinical profiles of ATTR cardiac amyloidosis with different genotype is important to its early recognition.

BACKGROUND: Gly83Arg variation is a type of TTR mutation specific to the Chinese population. Patients of hereditary transthyretin amyloidosis (ATTR) with Gly83Arg variation predominantly present with blurred vision and most of these cases are reported by ophthalmologists. There is currently no systematic assessment of extraocular features of ATTR with Gly83Arg variation.
METHODS: Six patients and two asymptomatic carriers with molecularly confirmed Gly83Arg variation of ATTR from three unrelated families were identified by sequencing the TTR gene. The clinical, electrophysiological, ultrasonic, and pathological data were collected and analyzed.
RESULTS: This study included six patients and two carriers with TTR Gly83Arg mutation, all of whom came from the Han nationality of China. The average age of onset for the six patients was 39 years, and the course of disease ranged from 5 to 19 years. All the patients started with blurred vision, which was diagnosed as vitreous opacity (VO). Most of the patients developed sensory-motor polyneuropathies over years or even more than a decade (4-15 years) after VO. However, the heterogeneity of peripheral neuropathies among these patients remained large between families. Autonomic impairment also occurred after VO, with varying degrees of abnormalities seen in the associated autonomic assessments. None of the patients had any symptoms of cardiac impairment, but abnormal results were found in examinations. A combined biopsy of the sural nerve and muscle was also performed. Nerve pathology revealed the moderately reduced myelinated nerve fiber density and muscle pathology showed predominant neurogenic impairment accompanied by possible myogenic impairment.
CONCLUSIONS: This is a detailed account of Gly83Arg mutation-related ATTR, focusing on the extraocular presentations of this special variant in Chinese. Clinical features of this variant are early-onset, ocular involvement predominance, neurological, and cardiac involvement along with the disease, and relatively long survival.

Misfolding and aggregation of transthyretin (TTR) is widely known to be responsible for a progressive systemic disorder called amyloid transthyretin (ATTR) amyloidosis. Studies suggest that TTR aggregation is initiated by a rate-limiting dissociation of the homo-tetramer into its monomers, which can rapidly misfold and self-assemble into amyloid fibril. Thus, exploring conformational change involved in TTR monomer misfolding is of vital importance for understanding the pathogenesis of ATTR amyloidosis. In this work, microsecond timescale hybrid-resolution molecular dynamics (MD) simulations combined with Markov state model (MSM) analysis were performed to investigate the misfolding mechanism of the TTR monomer. The results indicate that a macrostate with partially unfolded conformations may serve as the misfolded state of the TTR monomer. This misfolded state was extremely stable with a very large equilibrium probability of about 85.28%. With secondary structure analysis, we found the DAGH sheet in this state to be significantly destroyed. The CBEF sheet was relatively stable and sheet structure was maintained. However, the F-strand in this sheet was likely to move away from E-strand and reform a new β-sheet with the H-strand. This observation is consistent with experimental finding that F and H strands in the outer edge drive the misfolding of TTR. Finally, transition pathways from a near native state to this misfolded macrostate showed that the conformational transition can occur either through a native-like β-sheet intermediates or through partially unfolded intermediates, while the later appears to be the main pathway. As a whole, we identified a potential misfolded state of the TTR monomer and elucidated the misfolding pathway for its conformational transition. This work can provide a valuable theoretical basis for understanding of TTR aggregation and the pathogenesis of ATTR amyloidosis at the atomic level.