Hereditary ATTR amyloidosis

Characterization of Isolated Amyloid Myopathy.
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Characterization of Isolated Amyloid Myopathy.

Eur J Neurol. 2017 Sep 09;:

Authors: Liewluck T, Milone M

BACKGROUND AND PURPOSE: Amyloid myopathy frequently occurs in the setting of systemic amyloidosis and less commonly in isolation (isolated amyloid myopathy). Anoctaminopathy-5 and dysferlinopathy were recently recognized as causes of isolated amyloid myopathy. The present study aimed to characterize the isolated amyloid myopathy and to compare it with amyloid myopathy associated with systemic amyloidosis.
METHODS: We searched Muscle Laboratory database to identify patients with pathologically-confirmed amyloid myopathy and were seen in neurology clinics between January 1998 and September 2016. Patients with monoclonal gammopathy, peripheral neuropathy, organomegaly or symptoms or pathologic evidence of amyloid deposition outside skeletal muscle were classified as having systemic amyloidosis-associated myopathy.
RESULTS: Fifty-two patients were identified, including 14 isolated amyloid myopathy (8 anoctaminopathy-5, 2 dysferlinopathy, and 4 genetically-unknown) and 38 systemic amyloidosis (32 immunoglobulin light chain amyloidosis, 4 familial amyloid polyneuropathy, and 2 senile systemic amyloidosis). Compared to patients with systemic amyloidosis, isolated amyloid myopathy patients had: a younger age of onset (median, 41.5 versus 65 years), no dysphagia (0% versus 26%) or weight loss (0% versus 26%), but more frequent calf atrophy (57% versus 0%), small collections of inflammatory cells on muscle biopsy (43% versus 0%) and asymptomatic hyperCKemia at onset (21% versus 0%). All isolated amyloid myopathy patients had creatine kinase values greater than 2.5-times the upper limit of normal.
CONCLUSIONS: Isolated amyloid myopathy accounts for 27% of patients with amyloid myopathy, and mostly due to anoctaminopathy-5. There are various clinical and laboratory parameters that can help differentiating isolated amyloid myopathy from systemic amyloidosis. This article is protected by copyright. All rights reserved.

PMID: 28888072 [PubMed - as supplied by publisher]