A recent review of patients presenting with rhabdomyolysis due to (mainly MHS-associated) dominant RYR1 mutation showed that muscle biopsy findings were often non-specific, but may feature “RYR1-compatible” findings including irregular internal architecture or core-like structures, increased internal nuclei, type 1 fibre predominance and pinprick fibres expressing neonatal myosin [3]. The gene discussed is RYR1; the disease is rhabdomyolysis.