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Kim ES, Casey JG, Tao BS, Mansur A, Mathiyalagan N, Wallace ED, Ehrmann BM, Gupta VA. Intrinsic and extrinsic regulation of rhabdomyolysis susceptibility by Tango2. Dis Model Mech 2023; 16:dmm050092. [PMID: 37577943 PMCID: PMC10499024 DOI: 10.1242/dmm.050092] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/09/2023] [Indexed: 08/15/2023] Open
Abstract
Rhabdomyolysis is a clinical emergency characterized by severe muscle damage, resulting in the release of intracellular muscle components, which leads to myoglobinuria and, in severe cases, acute kidney failure. Rhabdomyolysis is caused by genetic factors linked to increased disease susceptibility in response to extrinsic triggers. Recessive mutations in TANGO2 result in episodic rhabdomyolysis, metabolic crises, encephalopathy and cardiac arrhythmia. The underlying mechanism contributing to disease onset in response to specific triggers remains unclear. To address these challenges, we created a zebrafish model of Tango2 deficiency. Here, we demonstrate that the loss of Tango2 in zebrafish results in growth defects, early lethality and increased susceptibility of skeletal muscle defects in response to extrinsic triggers, similar to TANGO2-deficient patients. Using lipidomics, we identified alterations in the glycerolipid pathway in tango2 mutants, which is critical for membrane stability and energy balance. Therefore, these studies provide insight into key disease processes in Tango2 deficiency and have increased our understanding of the impacts of specific defects on predisposition to environmental triggers in TANGO2-related disorders.
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Affiliation(s)
- Euri S. Kim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Jennifer G. Casey
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Brian S. Tao
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Arian Mansur
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Nishanthi Mathiyalagan
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - E. Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Brandie M. Ehrmann
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Vandana A. Gupta
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
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van den Bersselaar LR, van Alfen N, Kruijt N, Kamsteeg EJ, Fernandez-Garcia MA, Treves S, Riazi S, Yang CY, Malagon I, van Eijk LT, van Engelen BGM, Scheffer GJ, Jungbluth H, Snoeck MMJ, Voermans NC. Muscle Ultrasound Abnormalities in Individuals with RYR1-Related Malignant Hyperthermia Susceptibility. J Neuromuscul Dis 2023:JND230018. [PMID: 37154182 DOI: 10.3233/jnd-230018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
BACKGROUND Variants in RYR1, the gene encoding the ryanodine receptor-1, can give rise to a wide spectrum of neuromuscular conditions. Muscle imaging abnormalities have been demonstrated in isolated cases of patients with a history of RYR1-related malignant hyperthermia (MH) susceptibility. OBJECTIVE To provide insights into the type and prevalence of muscle ultrasound abnormalities and muscle hypertrophy in patients carrying gain-of-function RYR1 variants associated with MH susceptibility and to contribute to delineating the wider phenotype, optimizing the diagnostic work-up and care for of MH susceptible patients. METHODS We performed a prospective cross-sectional observational muscle ultrasound study in patients with a history of RYR1-related MH susceptibility (n = 40). Study procedures included a standardized history of neuromuscular symptoms and a muscle ultrasound assessment. Muscle ultrasound images were analyzed using a quantitative and qualitative approach and compared to reference values and subsequently subjected to a screening protocol for neuromuscular disorders. RESULTS A total of 15 (38%) patients had an abnormal muscle ultrasound result, 4 (10%) had a borderline muscle ultrasound screening result, and 21 (53%) had a normal muscle ultrasound screening result. The proportion of symptomatic patients with an abnormal result (11 of 24; 46%) was not significantly higher compared to the proportion of asymptomatic patients with an abnormal ultrasound result (4 of 16; 25%) (P = 0.182). The mean z-scores of the biceps brachii (z = 1.45; P < 0.001), biceps femoris (z = 0.43; P = 0.002), deltoid (z = 0.31; P = 0.009), trapezius (z = 0.38; P = 0.010) and the sum of all muscles (z = 0.40; P < 0.001) were significantly higher compared to 0, indicating hypertrophy. CONCLUSIONS Patients with RYR1 variants resulting in MH susceptibility often have muscle ultrasound abnormalities. Frequently observed muscle ultrasound abnormalities include muscle hypertrophy and increased echogenicity.
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Affiliation(s)
- Luuk R van den Bersselaar
- Department of Anesthesiology, Malignant Hyperthermia Investigation Unit, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands
- Department of Neurology, Clinical Neuromuscular Imaging Group, Donders Institutefor Brain, Cognition and Behaviour, Radboud University MedicalCenter, Nijmegen, The Netherlands
| | - Nens van Alfen
- Department of Neurology, Clinical Neuromuscular Imaging Group, Donders Institutefor Brain, Cognition and Behaviour, Radboud University MedicalCenter, Nijmegen, The Netherlands
| | - Nick Kruijt
- Department of Neurology, Clinical Neuromuscular Imaging Group, Donders Institutefor Brain, Cognition and Behaviour, Radboud University MedicalCenter, Nijmegen, The Netherlands
- Department of Primary and Community Care, Radboudumc, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Miguel A Fernandez-Garcia
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy's and St Thomas' Hospital NHS Foundation Trust, London, UK
| | - Susan Treves
- Departments of Biomedicine and Neurology, Neuromuscular research Group, University Hospital Basel, Basel, Switzerland
| | - Sheila Riazi
- Department of Anesthesia, Malignant Hyperthermia Investigation Unit, University Health Network, University of Toronto, Toronto, Canada
| | - Chu-Ya Yang
- Department of Anesthesiology, Malignant Hyperthermia Investigation Unit, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands
| | - Ignacio Malagon
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lucas T van Eijk
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Baziel G M van Engelen
- Department of Neurology, Clinical Neuromuscular Imaging Group, Donders Institutefor Brain, Cognition and Behaviour, Radboud University MedicalCenter, Nijmegen, The Netherlands
| | - Gert-Jan Scheffer
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy's and St Thomas' Hospital NHS Foundation Trust, London, UK
- Randall Division for Cell and Molecular Biophysics, Muscle Signalling Section, Faculty of Life Sciences and Medicine, King's College, London, UK
| | - Marc M J Snoeck
- Department of Anesthesiology, Malignant Hyperthermia Investigation Unit, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands
| | - Nicol C Voermans
- Department of Neurology, Clinical Neuromuscular Imaging Group, Donders Institutefor Brain, Cognition and Behaviour, Radboud University MedicalCenter, Nijmegen, The Netherlands
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O’Connor TN, van den Bersselaar LR, Chen YS, Nicolau S, Simon B, Huseth A, Todd JJ, Van Petegem F, Sarkozy A, Goldberg MF, Voermans NC, Dirksena RT. RYR-1-Related Diseases International Research Workshop: From Mechanisms to Treatments Pittsburgh, PA, U.S.A., 21-22 July 2022. J Neuromuscul Dis 2023; 10:135-154. [PMID: 36404556 PMCID: PMC10023165 DOI: 10.3233/jnd-221609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Thomas N. O’Connor
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Luuk R. van den Bersselaar
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
- Malignant Hyperthermia Investigation Unit, Department of Anaesthesia, Canisius Wilhelmina Hospital, Nijmegen, the Netherlands
| | - Yu Seby Chen
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Stefan Nicolau
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | | | | | - Joshua J. Todd
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Anna Sarkozy
- The Dubowitz Neuromuscular Centre, Institute of Child Health and Great Ormond Street Hospital for Children, London, UK
| | | | - Nicol C. Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Robert T. Dirksena
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Janssens L, De Puydt J, Milazzo M, Symoens S, De Bleecker JL, Herdewyn S. Risk of malignant hyperthermia in patients carrying a variant in the skeletal muscle ryanodine receptor 1 gene. Neuromuscul Disord 2022; 32:864-869. [PMID: 36283893 DOI: 10.1016/j.nmd.2022.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 12/15/2022]
Abstract
Malignant hyperthermia is a life-threatening disorder, which can be prevented by avoiding certain anesthetic agents. Pathogenic variants in the skeletal muscle ryanodine receptor 1-gene are linked to malignant hyperthermia. We retrospectively studied 15 patients who presented to our clinic with symptoms of muscle dysfunction (weakness, myalgia or cramps) and were later found to have a variant in the skeletal muscle ryanodine receptor 1-gene. Symptoms, creatine kinase levels, electromyography, muscle biopsy and in vitro contracture test results were reviewed. Six out of the eleven patients, with a variant of unknown significance in the skeletal muscle ryanodine receptor 1-gene, had a positive in vitro contracture test, indicating malignant hyperthermia susceptibility. In one patient, with two variants of unknown significance, both variants were required to express the malignant hyperthermia-susceptibility trait. Neurologists should consider screening the skeletal muscle ryanodine receptor 1-gene in patients with myalgia or cramps, even when few to no abnormalities on ancillary testing.
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Affiliation(s)
- Lise Janssens
- Faculty of medical and health sciences, Ghent University, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - Joris De Puydt
- University Hospital of Antwerp, Drie Eikenstraat 655, Edegem 2650, Belgium; Faculty of medical and health sciences, Antwerp University, Prinsstraat 13, Antwerp 2000, Belgium
| | - Mauro Milazzo
- Center for Medical Genetics Ghent, Ghent University Hospital, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - Sofie Symoens
- Faculty of medical and health sciences, Ghent University, Corneel Heymanslaan 10, Ghent 9000, Belgium; Center for Medical Genetics Ghent, Ghent University Hospital, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - Jan L De Bleecker
- Faculty of medical and health sciences, Ghent University, Corneel Heymanslaan 10, Ghent 9000, Belgium; Department of Neurology, Ghent University Hospital, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - Sarah Herdewyn
- Department of Neurology, Ghent University Hospital, Corneel Heymanslaan 10, Ghent 9000, Belgium.
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van den Bersselaar LR, Jungbluth H, Kruijt N, Kamsteeg EJ, Fernandez-Garcia MA, Treves S, Riazi S, Malagon I, van Eijk LT, van Alfen N, van Engelen BGM, Scheffer GJ, Snoeck MMJ, Voermans NC. Neuromuscular symptoms in patients with RYR1-related malignant hyperthermia and rhabdomyolysis. Brain Commun 2022; 4:fcac292. [PMID: 36751502 PMCID: PMC9897183 DOI: 10.1093/braincomms/fcac292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/21/2022] [Accepted: 11/04/2022] [Indexed: 11/12/2022] Open
Abstract
Malignant hyperthermia and exertional rhabdomyolysis have conventionally been considered episodic phenotypes that occur in otherwise healthy individuals in response to an external trigger. However, recent studies have demonstrated a clinical and histopathological continuum between patients with a history of malignant hyperthermia susceptibility and/or exertional rhabdomyolysis and RYR1-related congenital myopathies. We hypothesize that patients with a history of RYR1-related exertional rhabdomyolysis or malignant hyperthermia susceptibility do have permanent neuromuscular symptoms between malignant hyperthermia or exertional rhabdomyolysis episodes. We performed a prospective cross-sectional observational clinical study of neuromuscular features in patients with a history of RYR1-related exertional rhabdomyolysis and/or malignant hyperthermia susceptibility (n = 40) compared with healthy controls (n = 80). Patients with an RYR1-related congenital myopathy, manifesting as muscle weakness preceding other symptoms as well as other (neuromuscular) diseases resulting in muscle weakness were excluded. Study procedures included a standardized history of neuromuscular symptoms, a review of all relevant ancillary diagnostic tests performed up to the point of inclusion and a comprehensive, standardized neuromuscular assessment. Results of the standardized neuromuscular history were compared with healthy controls. Results of the neuromuscular assessment were compared with validated reference values. The proportion of patients suffering from cramps (P < 0.001), myalgia (P < 0.001) and exertional myalgia (P < 0.001) was higher compared with healthy controls. Healthcare professionals were consulted because of apparent neuromuscular symptoms by 17/40 (42.5%) patients and 7/80 (8.8%) healthy controls (P < 0.001). Apart from elevated creatine kinase levels in 19/40 (47.5%) patients and mild abnormalities on muscle biopsies identified in 13/16 (81.3%), ancillary investigations were normal in most patients. The Medical Research Council sum score, spirometry and results of functional measurements were also mostly normal. Three of 40 patients (7.5%) suffered from late-onset muscle weakness, most prominent in the proximal lower extremity muscles. Patients with RYR1 variants resulting in malignant hyperthermia susceptibility and/or exertional rhabdomyolysis frequently report additional neuromuscular symptoms such as myalgia and muscle cramps compared with healthy controls. These symptoms result in frequent consultation of healthcare professionals and sometimes in unnecessary invasive diagnostic procedures. Most patients do have normal strength at a younger age but may develop muscle weakness later in life.
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Affiliation(s)
- Luuk R van den Bersselaar
- Correspondence to: Luuk R van den Bersselaar Weg door Jonkerbos 100, 6532 SZ Nijmegen, The Netherlands E-mail:
| | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy’s and St Thomas’ Hospital NHS Foundation Trust, SE1 7EH London, UK,Randall Centre of Cell and Molecular Biophysics, Muscle Signaling Section, Faculty of Life Sciences and Medicine (FoLSM), King's College, WC2R 2LS London, UK
| | - Nick Kruijt
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Miguel A Fernandez-Garcia
- Department of Paediatric Neurology, Neuromuscular Service, Evelina Children's Hospital, Guy’s and St Thomas’ Hospital NHS Foundation Trust, SE1 7EH London, UK
| | - Susan Treves
- Departments of Biomedicine and Neurology, Neuromuscular research Group, University Hospital Basel, 4031 Basel, Switzerland
| | - Sheila Riazi
- Department of Anesthesia, Malignant Hyperthermia Investigation Unit, University Health Network, University of Toronto, M5s 1a4 Toronto, Ontario, Canada
| | - Ignacio Malagon
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Lucas T van Eijk
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Nens van Alfen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Baziel G M van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Gert-Jan Scheffer
- Department of Anesthesiology, Pain and Palliative Medicine, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
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Riazi S, Bersselaar LRVD, Islander G, Heytens L, Snoeck MMJ, Bjorksten A, Gillies R, Dranitsaris G, Hellblom A, Treves S, Kunst G, Voermans NC, Jungbluth H. Pre-operative exercise and pyrexia as modifying factors in malignant hyperthermia (MH). Neuromuscul Disord 2022; 32:628-634. [PMID: 35738978 DOI: 10.1016/j.nmd.2022.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 11/19/2022]
Abstract
Malignant hyperthermia (MH) is a life-threatening reaction triggered by volatile anesthetics and succinylcholine. MH is caused by mutations in the skeletal muscle ryanodine receptor (RYR1) gene, as is rhabdomyolysis triggered by exertion and/or pyrexia. The discrepancy between the prevalence of risk genotypes and actual MH incidence remains unexplained. We investigated the role of pre-operative exercise and pyrexia as potential MH modifying factors. We included cases from 5 MH referral centers with 1) clinical features suggestive of MH, 2) confirmation of MH susceptibility on Contracture Testing (IVCT or CHCT) and/or RYR1 genetic testing, and a history of 3) strenuous exercise within 72 h and/or pyrexia >37.5 °C prior to the triggering anesthetic. Characteristics of MH-triggering agents, surgery and succinylcholine use were collected. We identified 41 cases with general anesthesias resulting in an MH event (GA+MH, n = 41) within 72 h of strenuous exercise and/or pyrexia. We also identified previous general anesthesias without MH events (GA-MH, n = 51) in the index cases and their MH susceptible relatives. Apart from pre-operative exercise and/or pyrexia, trauma and acute abdomen as surgery indications, emergency surgery and succinylcholine use were also more common with GA+MH events. These observations suggest a link between pre-operative exercise, pyrexia and MH.
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Affiliation(s)
- Sheila Riazi
- Department of Anesthesia, Malignant Hyperthermia Investigation Unit, University Health Network, University of Toronto, Toronto, Canada
| | | | | | - Luc Heytens
- Department of Anaesthesiology, University Hospital Antwerp, Edegem, Belgium
| | - Marc M J Snoeck
- Malignant Hyperthermia Investigation Unit, Canisius Wilhelmina Hospital, Nijmegen, The Netherlands
| | - Andrew Bjorksten
- Department of Anaesthesia and Pain Management, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Robyn Gillies
- Department of Anaesthesia and Pain Management, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - George Dranitsaris
- Department of Anesthesia, Malignant Hyperthermia Investigation Unit, University Health Network, University of Toronto, Toronto, Canada
| | - Anna Hellblom
- Department of Intensive and Perioperative Medicine, Skane University Hospital, Lund, Sweden; Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Susan Treves
- Department of Biomedicine, Basel University Hospital, Basel University, Basel, Switzerland
| | - Gudrun Kunst
- Department of Anaesthetics and Pain Therapy, King's College Hospital, London, UK; School of Cardiovascular Medicine and Sciences, King's College London, London, UK
| | - Nicol C Voermans
- Department of Neurology, Radboud University, Nijmegen, The Netherlands
| | - Heinz Jungbluth
- Randall Centre Cell and Molecular Biophysics, Muscle Signalling Section, King's College, London, UK; Department of Paediatric Neurology, Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK.
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Referral indications for malignant hyperthermia susceptibility diagnostics in patients without adverse anesthetic events in the era of next-generation sequencing. Anesthesiology 2022; 136:940-953. [PMID: 35285867 DOI: 10.1097/aln.0000000000004199] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The introduction of next-generation sequencing into the diagnosis of neuromuscular disorders has resulted in an increased number of newly identified RYR1 variants. We hypothesize that there is an increased referral of patients to Malignant Hyperthermia (MH)-units without a personal/family history of adverse anesthetic events suspected for MH. This retrospective multicenter cohort study evaluates patient referral indications and outcomes for those without a history of an adverse anesthetic event. METHODS Patients referred between 2010-2019 to the MH-units in Antwerp, Lund, Nijmegen and Toronto were included. Previously tested patients and relatives of previously tested patients were excluded. Data collection included demographics, referral details, muscle contracture and genetic testing results including REVEL scores. Referral indications were categorized into those with a personal/family history of adverse anesthetic event and other indications including exertional and/or recurrent rhabdomyolysis, RYR1 variant(s) detected in diagnostic testing in the neuromuscular clinic without a specific diagnosis (in a family member), diagnosed RYR1-related myopathy (in a family member), idiopathically elevated resting creatine kinase values, exertional heat stroke and other. RESULTS A total of 520 medical records were included, with the three most frequent referral indications; personal history of an adverse anesthetic event (211/520; 40.6%), family history of an adverse anesthetic event (115/520; 22.1%), and exertional and/or recurrent rhabdomyolysis (46/520; 8.8%). The proportion of patients referred without a personal/family history of an adverse anesthetic event increased to 43.6% (133/305) between 2015-2019 compared to 28.4% (61/215) in 2010-2014 (P<0.001). Patients with a personal/family history of an adverse anesthetic event were more frequently diagnosed as MH susceptible (133/220; 60.5%) than those without (47/120; 39.2%), (P < 0.001). Due to missing data, 180 medical records were excluded. CONCLUSION The proportion of patients referred to MH-units without a personal/family history of an adverse anesthetic event has increased, with 39.2% (47/120) diagnosed as MH susceptible.
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