Case reportWidening the spectrum of filamin-C myopathy: Predominantly proximal myopathy due to the p.A193T mutation in the actin-binding domain of FLNC

- Mutations in the actin-binding domain of FLNC may present as proximal myopathy.
- Mutations in FLNC have to be considered even if typical histological features are absent.
- Muscle imaging can help to distinguish different FLNC-related myopathy types.

We report three patients with a predominantly proximal myopathy due to p.A193T mutation in the actin-binding domain of FLNC, which has so far only been associated with a distal myopathy. They presented with a late onset myopathy characterized by predominant limb-girdle and proximal weakness. We describe the clinical, electrophysiological, pathological, muscle imaging and genetic features. One of our patients did not have typical histological features for a myofibrillar myopathy in muscle biopsy. This observation is important for the recognition of the full clinical spectrum of filamin-C-related myopathies. Muscle imaging has an important role in distinguishing the different filamin-C myopathy types.