Clinical and biochemical characterization of asymptomatic carriers and symptomatic patients with hereditary transthyretin amyloidosis caused by TTR V30L mutation
Hao Jiao, Mengdie Wang, Kang Du, Jialu Sun, Xujun Chu, Junsu Yang, He Lv, Wei Zhang, Zhaoxia Wang, Yun Yuan, Yu Liu, Lingchao Meng
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Abstract
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.
期刊介绍:
Neurological Sciences is intended to provide a medium for the communication of results and ideas in the field of neuroscience. The journal welcomes contributions in both the basic and clinical aspects of the neurosciences. The official language of the journal is English. Reports are published in the form of original articles, short communications, editorials, reviews and letters to the editor. Original articles present the results of experimental or clinical studies in the neurosciences, while short communications are succinct reports permitting the rapid publication of novel results. Original contributions may be submitted for the special sections History of Neurology, Health Care and Neurological Digressions - a forum for cultural topics related to the neurosciences. The journal also publishes correspondence book reviews, meeting reports and announcements.