The incidence of acute anesthetic-associated MH varied from 1 in 4000 to 1 in 250,000 anesthetics over a 6.5-year period, depending on the details of the clinical definition of MH and the type of anesthetic drugs to which the patient was exposed.[1]Hopkins PM, Girard T, Dalay S, et al. Malignant hyperthermia 2020: guideline from the Association of Anaesthetists. Anaesthesia. 2021 May;76(5):655-64.
https://www.doi.org/10.1111/anae.15317
http://www.ncbi.nlm.nih.gov/pubmed/33399225?tool=bestpractice.com
[16]Ording H. Incidence of malignant hyperthermia in Denmark. Anesth Analg. 1985 Jul;64(7):700-4.
http://www.ncbi.nlm.nih.gov/pubmed/4014731?tool=bestpractice.com
It has been estimated that the prevalence of a genetic substrate responsible for susceptibility to MH is present in at least 1 in 3000 people.[17]Monnier N, Krivosic-Horber R, Payen JF, et al. Presence of two different genetic traits in malignant hyperthermia families: implications for genetics analysis, diagnosis, and incidence of malignant hyperthermia susceptibility. Anesthesiology. 2002 Nov;97(5):1067-74.
http://www.ncbi.nlm.nih.gov/pubmed/12411788?tool=bestpractice.com
[18]Ibarra MCA, Wu S, Murayama K, et al. Malignant hyperthermia in Japan: mutation screening of the entire ryanodine receptor type 1 gene coding region by direct sequencing. Anesthesiology. 2006 Jun;104(6):1146-54.
http://www.ncbi.nlm.nih.gov/pubmed/16732084?tool=bestpractice.com
[19]Brandom BW, Bina S, Wong CA, et al. Ryanodine receptor type 1 gene variants in the malignant hyperthermia-susceptible population of the United States. Anesth Analg. 2013 May;116(5):1078-86.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3633164
http://www.ncbi.nlm.nih.gov/pubmed/23558838?tool=bestpractice.com
[20]Gonsalves SG, Ng D, Johnston JJ, et al; NISC Comparative Sequencing Program. Using exome data to identify malignant hyperthermia susceptibility mutations. Anesthesiology. 2013 Nov;119(5):1043-53.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4077354
http://www.ncbi.nlm.nih.gov/pubmed/24195946?tool=bestpractice.com
This is based in part on the observation of compound heterozygotes of ryanodine receptor gene type 1 (RYR1) variants that have been found in people susceptible to MH in Europe, North America, and Japan.[21]Kraeva N, Riazi S, Loke J, et al. Ryanodine receptor type 1 gene mutations found in the Canadian malignant hyperthermia population. Can J Anaesth. 2011 Jun;58(6):504-13.
http://link.springer.com/article/10.1007/s12630-011-9494-6/fulltext.html
http://www.ncbi.nlm.nih.gov/pubmed/21455645?tool=bestpractice.com
RYR1 variants have also been found in families where MH events and deaths occurred in South America, South Africa, Australia, New Zealand, Korea, and China.[22]Chan B, Chen SP, Wong WC, et al. RYR1-related central core myopathy in a Chinese adolescent boy. Hong Kong Med J. 2011 Feb;17(1):67-70.
http://www.hkmj.org/article_pdfs/hkm1102p67.pdf
http://www.ncbi.nlm.nih.gov/pubmed/21282829?tool=bestpractice.com
[23]Gillies RL, Bjorksten AR, Du Sart D, et al. Analysis of the entire ryanodine receptor type 1 and alpha 1 subunit of the dihydropyridine receptor (CACNA1S) coding regions for variants associated with malignant hyperthermia in Australian families. Anaesth Intensive Care. 2015 Mar;43(2):157-66.
http://www.ncbi.nlm.nih.gov/pubmed/25735680?tool=bestpractice.com
However, RYR1 mutations may account for only 50% of MH cases, so measures of MH susceptibility prevalence obtained using RYR1 mutations alone are likely to be underestimates.[24]Sambuughin N, Holley H, Muldoon S, et al. Screening of the entire ryanodine receptor type 1 coding region for sequence variants associated with malignant hyperthermia susceptibility in the North American population. Anesthesiology. 2005 Mar;102(3):515-21.
http://www.ncbi.nlm.nih.gov/pubmed/15731587?tool=bestpractice.com
[25]Levano S, Vukcevic M, Singer M, et al. Increasing the number of diagnostic mutations in malignant hyperthermia. Human Mutat. 2009 Apr;30(4):590-8.
http://www.ncbi.nlm.nih.gov/pubmed/19191329?tool=bestpractice.com
The reported yields vary with the population selected and the details of the genetic test.[20]Gonsalves SG, Ng D, Johnston JJ, et al; NISC Comparative Sequencing Program. Using exome data to identify malignant hyperthermia susceptibility mutations. Anesthesiology. 2013 Nov;119(5):1043-53.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4077354
http://www.ncbi.nlm.nih.gov/pubmed/24195946?tool=bestpractice.com
MH, on average, presents during the second or third exposure to a triggering agent and in patients in their late teenage years. MH episodes are reported more often in men than in women.[5]Riazi S, Larach MG, Hu C, et al. Malignant hyperthermia in Canada: characteristics of index anesthetics in 129 malignant hyperthermia susceptible probands. Anesth Analg. 2014 Feb;118(2):381-7.
http://www.ncbi.nlm.nih.gov/pubmed/23842196?tool=bestpractice.com
[6]Larach MG, Gronert GA, Allen GC, et al. Clinical presentation, treatment, and complications of malignant hyperthermia in North America from 1987 to 2006. Anesth Analg. 2010 Feb 1;110(2):498-507.
http://journals.lww.com/anesthesia-analgesia/pages/articleviewer.aspx?year=2010&issue=02000&article=00039&type=Fulltext
http://www.ncbi.nlm.nih.gov/pubmed/20081135?tool=bestpractice.com
[26]Sumitani M, Uchida K, Yasunaga H, et al. Prevalence of malignant hyperthermia and relationship with anesthetics in Japan: data from the diagnosis procedure combination database. Anesthesiology. 2011 Jan;114(1):84-90.
http://www.ncbi.nlm.nih.gov/pubmed/21169796?tool=bestpractice.com
[27]Visoiu M, Young MC, Wieland K, et al. Anesthetic drugs and onset of malignant hyperthermia. Anesth Analg. 2014 Feb;118(2):388-96.
http://www.ncbi.nlm.nih.gov/pubmed/24445637?tool=bestpractice.com
The North American Malignant Hyperthermia Registry
Opens in new window Males are more likely than females to be diagnosed with MH by the caffeine halothane contracture test (CHCT).[28]Butala B, Brandom B. Muscular body build and male sex are independently associated with malignant hyperthermia susceptibility. Can J Anaesth. 2017 Apr;64(4):396-401.
http://www.ncbi.nlm.nih.gov/pubmed/28063098?tool=bestpractice.com