Abstract Details

Title A Novel Case of Overlapping of Myotonic Dystrophy Type 2 and Bethlem Congenital Muscular Dystrophy

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P5 - Poster Session 5 (5:30 PM-6:30 PM)

Poster/Presentation
Number 12-017

Objective

To describe a unique case of clinical and genetic overlap

Background Dominant transmission of Collagen 6A3 gene mutation may be associated with Bethlem congenital muscular dystrophy characterized by proximal muscle weakness. Myotonic dystrophy type 2 affects distal and proximal limbs. Co-existence of genetically confirmed presence of both has not been described.

Design/Methods

This patient was seen at our clinic, a tertiary referral center for Central Pennsylvania.

Results A 45-year-old right handed woman with 20 year history of proximal leg weakness associated with cramps in the arms, bilateral hearing loss and memory impairment. Physical examination showed mild proximal lower extremity weakness, brisk reflexes, flexor plantar responses, without myotonia. Her myotonic dystrophy type 2 (DM2) was confirmed with CNBP mutation with CCTG expansion of 14,970 pairs. She also was found to have COL6A3 gene mutation with a R2290C variant, previously described as pathogenic. Both autosomal recessive and dominant forms of COL6A3 related disease transmission have been described. Her daughter was clinically diagnosed with Bethlem Congenital muscular dystrophy due to the same R2290C Col 6A3 variant, which was therefore an inherited mutation, and the condition was not a carrier state only. The daughter was negative for Myotonic dystrophy types 1 and 2. Systemic endocrine involvement, unaccounted hearing loss and memory impairment were reflective of activity of her Myotonic dystrophy. For the mother, the relative contribution of two conditions for her symptoms were hard to be determined.

Conclusions Detection of clinically and genetically heterogeneous neuromuscular diseases (NMDs) can be challenging in symptomatic patients. It is usual practice nowadays for targeted gene sequencing. Phenotype variants not explained on the basis of underlying NMD should lead to additional genetic screening, expanding the phenotype/genotype relationship. Endocrine, ophthalmological as well as cardiac care for this patient might have been delayed or missed, if the concomitant diagnosis of Myotonic dystrophy were not made.

Authors/Disclosures
Mayur Chalia, MD PRESENTER	Dr. Chalia has nothing to disclose.
Sankar Bandyopadhyay, MD, FAAN (Penn State Hershey Medical Center)	Dr. Bandyopadhyay has nothing to disclose.

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