Nick Kruijt*, Luuk Van den Bersselaar, Marc Snoeck, Kees Kramers, Sheila Riazi, Coen Bongers, Susan Treves, Heinz Jungbluth and Nicol Voermans Pages 2 - 14 ( 13 )
Variants in the ryanodine receptor-1 gene (RYR1) have been associated with a wide range of neuromuscular conditions, including various congenital myopathies and malignant hyperthermia (MH). More recently, a number of RYR1 variants, mostly MH-associated, have been demonstrated to contribute to rhabdomyolysis events not directly related to anesthesia in otherwise healthy individuals. This review focuses on RYR1-related rhabdomyolysis in the context of several clinical presentations (i.e., exertional rhabdomyolysis, exertional heat illnesses and MH), and conditions involving a similar hypermetabolic state, in which RYR1 variants may be present (i.e., neuroleptic malignant syndrome and serotonin syndrome). The variety of triggers that can evoke rhabdomyolysis, on their own or in combination, as well as the number of potentially associated complications, illustrates that this is a condition relevant to several medical disciplines. External triggers include but are not limited to strenuous physical exercise, especially if unaccustomed or performed under challenging environmental conditions (e.g., high ambient temperature or humidity), alcohol/illicit drugs, prescription medication (in particular statins, other anti-lipid agents, antipsychotics and antidepressants) infection, or heat. Amongst all patients presenting with rhabdomyolysis, genetic susceptibility is present in a proportion, with RYR1 being one of the most common genetic causes. Clinical clues for a genetic susceptibility include recurrent rhabdomyolysis, creatine kinase (CK) levels above 50 times the upper limit of normal, hyperCKemia lasting for 8 weeks or longer, drug/medication doses insufficient to explain the rhabdomyolysis event, and positive family history. For the treatment or prevention of RYR1-related rhabdomyolysis, the RYR1 antagonist dantrolene can be administered, both in the acute phase or prophylactically in patients with a history of muscle cramps and/or recurrent rhabdomyolysis events. Aside from dantrolene, several other drugs are being investigated for their potential therapeutic use in RYR1-related disorders. These findings offer further therapeutic perspectives for humans, suggesting an important area for future research.
RYR1, Rhabdomyolysis, neuromuscular disorders, exertional rhabdomyolysis, exertional heat illness, malignant hyperthermia
Department of Neurology, Radboud University Medical Centre, Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, Malignant Hyperthermia Investigation Unit, Canisius Wilhelmina Hospital, Nijmegen, Department of Pharmacology and Toxicology, Radboud University Medical Centre, Nijmegen, Department of Anesthesiology and Pain Medicine, University Health Network, University of Toronto, Toronto, ON, Department of Physiology, Radboudumc, Nijmegen, Department of Biomedicine, University Hospital Basel, Basel, Department of Paediatric Neurology - Neuromuscular Service, Evelina Children’s Hospital, Guy’s & St Thomas’ NHS Foundation Trust, London, Department of Neurology, Radboud University Medical Centre, Nijmegen