Abstract Details

Title Case Report: Late Onset Myofibrillary Myopathy in a Patient with DES and LDB3 Mutations

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P3 - Poster Session 3 (11:45 AM-12:45 PM)

Poster/Presentation
Number 11-030

Objective To report a rare case of a 73-year-old presenting with distal extremity weakness and diagnosed with myofibrillar myopathy via the identification of two disease causing mutations in the genes – DES and ZASP/LDB3

Background Myofibrillar myopathies (MFM) refers to a group of rare distal myopathies caused by a heterogenous set of genetic mutations that encode proteins associated with the Z-disc. These conditions are characterized by abnormal protein aggregations and myofibrillar disintegrations. To date, few disease-causing mutations in genes have been identified, including autosomal dominant Desmin (DES) and Z-band alternatively spliced PDZ – motif containing protein (ZASP/LDB3). DES is an intermediate filament present in smooth, cardiac and skeletal muscles and plays a crucial role in the structural integrity of these muscles. ZASP is a Z-disk associated protein found in cardiac and skeletal muscles and though its functions is not well understood, it directly interacts with actin filaments.

Design/Methods N/A

Results

We present a 73-year-old woman with history of primary biliary cirrhosis and lumbar stenosis status post decompression with slowly progressive difficulty ambulating since her early 40s. The patient was found to have bilateral distal lower weakness with steppage gait with proximal upper extremities weakness of less severity. Electrodiagnostic testing and muscle biopsy showed features of neuropathy and myopathy without inflammation. Distal myopathic process was suspected, thus, genetic testing was sent and later revealed autosomal dominant heterozygous mutations in both the DES (c.407T>A) and ZASP (c.652C>T) genes, thereby confirming the diagnosis of myofibrillar myopathy.

Conclusions We describe a patient with distal myopathy found to have heterozygous inheritance pattern of two genes known to be associated with myofibrillar myopathy, suggesting a possible polygenic etiology with point mutations in DES and ZASP previously not known to be pathogenic.

Authors/Disclosures
Arnaud Batchou, DO (Northwell) PRESENTER	Dr. Batchou has nothing to disclose.
Mehwish Khan, DO (Northwell- SIUH)	Dr. Khan has nothing to disclose.
Umair Ahmed, MD (Staten Island University Hospital)	Dr. Ahmed has nothing to disclose.
Edward Yu, MD, FAAN (Northwell Health)	Dr. Yu has nothing to disclose.

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