Dominant mutations of the CACNA1S gene most often cause hypokalemic periodic paralysis or malignant hyperthermia.
The team at the Brussels Neuromuscular Reference Centre reports the case of a 65-year-old man with progressive proximal muscle weakness that began at the age of 35, without any transient paralysis:
- his mother, who had been in a wheelchair since the age of 55, and his brother, who had no permanent muscular weakness, had experienced periodic episodes of paralysis.
- biceps muscle biopsy showed atrophic fibers with numerous vacuoles containing tubular aggregates.
The authors wish to draw attention to this purely myopathic progressive form due to dominant CACNA1S mutations in young adults, particularly if the biopsy shows tubular aggregates.
