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Disease Modifying Treatments for Transthyretin Amyloidosis. J Cardiovasc Pharmacol 2021; 78:e641-e647. [PMID: 34321398 DOI: 10.1097/fjc.0000000000001115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 07/01/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT The transthyretin (TTR) amyloidoses result from misfolding of the protein leading to fibril formation and aggregation as amyloid deposits in predominantly the cardiovascular and nervous systems. Cardiac involvement can manifest as heart failure, arrhythmias, and valvular disease. Neurologic involvement can cause sensorimotor polyneuropathies, mononeuropathies, and dysautonomia. Previously, treatment has focused on management of these symptoms and disease sequelae, with a high rate of mortality due to the absence of disease modifying therapies. In this manuscript, we review novel treatments focusing on three mechanistic pathways: (1) silencing of the TTR gene to suppress production, (2) stabilizing of TTR tetramers to prevent misfolding, or (3) disrupting of existing TTR amyloid fibrils to promote reabsorption.
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Chiang MC, Yeh TY, Sung JY, Hsueh HW, Kao YH, Hsueh SJ, Chang KC, Feng FP, Lin YH, Chao CC, Hsieh ST. Early changes of nerve integrity in preclinical carriers of hereditary transthyretin Ala117Ser amyloidosis with polyneuropathy. Eur J Neurol 2021; 28:982-991. [PMID: 33369810 DOI: 10.1111/ene.14698] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/29/2020] [Accepted: 12/22/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND PURPOSE Disease-modifying therapies provide new horizons for hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) to slow neuropathic progression. Initiating treatment at the earliest time requires biomarkers reflecting both small- and large-fiber degeneration in carriers. METHODS This study included examinations of pathology (intraepidermal nerve fiber [IENF] density), physiology (nerve conduction studies, autonomic function test, and nerve excitability), and psychophysics (thermal thresholds) in carriers to compare to healthy controls and asymptomatic diabetic patients. RESULTS There were 43 carriers (44.2 ± 11.4 years, p.Ala117Ser in 42 carriers), 43 controls (43.4 ± 12.7 years) including 26 noncarrier families, and 50 asymptomatic diabetic patients (58.1 ± 9.5 years). Carriers had lower IENF densities than controls and similar densities as diabetic patients. Median nerve conduction parameters, especially distal motor latency, were the most frequent neurophysiological abnormality in carriers, could differentiate carriers from controls and diabetic patients, were correlated with IENF densities in carriers but not in controls and diabetic patients, and were correlated with nerve excitability parameters in carriers but not in controls. Fifteen carriers (34.9%) with electrophysiological evidence of median nerve entrapment at the wrist had lower IENF densities and more abnormal conduction parameters than carriers without. We defined nerve dysfunction index-the ratio of median distal motor latency to IENF density-which differentiated carriers from controls. CONCLUSIONS In late-onset ATTRv-PN carriers with predominant p.Ala117Ser, median conduction parameters were the most common neurophysiological abnormalities and served as surrogate signatures of small- and large-fiber impairment. Combination of median distal motor latency and IENF density can reflect early neuropathy in carriers.
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Affiliation(s)
- Ming-Chang Chiang
- Department of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan
| | - Ti-Yen Yeh
- Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Jia-Ying Sung
- Department of Neurology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Hsueh-Wen Hsueh
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Yi-Hui Kao
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Sung-Ju Hsueh
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Kai-Chieh Chang
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Fang-Ping Feng
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Yea-Huey Lin
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chi-Chao Chao
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Sung-Tsang Hsieh
- Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan.,Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University College of Medicine, Taipei, Taiwan.,Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan.,Center of Precision Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
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