Abstract Details

Title Adult-onset Bethlem Myopathy Masquerading as a Demyelinating Disorder: A Case Report from Puerto Rico

Topic General Neurology

Presentation(s) P3 - Poster Session 3 (5:00 PM-6:00 PM)

Poster/Presentation
Number 7-008

Objective Our objective was to describe an atypical presentation of adult-onset Bethlem myopathy in a Puerto Rican woman whose clinical and radiologic features initially suggested possible demyelinating etiology.

Background Bethlem myopathy (BM) is an uncommon, collagen-VI related muscular dystrophy caused by mutations in COL6A1, COL6A2 or COL6A3. It normally presents during childhood with symptoms such as progressive proximal weakness and joint contractures, though rare adult-onset cases do occur. Central nervous system demyelination and ocular symptoms are atypical of this disorder, and patients with MRI nonspecific white-matter lesions combined with optic dysfunction can be misdiagnosed with a demyelinating disorder. Few cases regarding Latino populations have been reported, demonstrating a clear research gap in an already rare disorder.

Design/Methods A 44-year old woman presented with upper extremity fatigability, “Christmas-tree” cataracts, bilateral hand contractions and progressive visual deterioration . Brain MRI revealed nonspecific left frontal subcortical and bilateral periventricular T2 hyperintensities. No spinal cord involvement was observed in MRI. Lumbar puncture was negative for CSF-restricted oligoclonal bands and showed a normal Igg index. Organic acids test was also negative. Genetic sequencing revealed a pathogenic COL6A3 variant: c.1708C>T (p.Gln570*). Additionally, it also uncovered several mutations related to muscular dystrophy type 2 (DM2). Whole exosome sequencing and a muscle biopsy are scheduled for December to further characterize the condition.

Results The combination of MRI abnormalities, ocular symptoms and slow myopathic progression provided suspicions of a demyelinating disorder, but the absence of oligoclonal bands and genetic testing showing a nonsense COL63A variant confirmed the diagnosis of Bethlem myopathy.

Conclusions

Although some of these symptoms have not been shown to occur in classic Bethlem myopathy presentation, this case serves to highlight how adult-onset cases can masquerade as a demyelinating disorder. Awareness of collagen-VI myopathies and the utilization of genetic testing when presented with atypical workups can help prevent misdiagnosis.

Authors/Disclosures
Ricardo E. Calderón Rivera, BS PRESENTER	Mr. Calderón Rivera has nothing to disclose.
Rhaisa Castrodad- Molina, MD	Dr. Castrodad- Molina has nothing to disclose.

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