Epigenetic allele silencing and variable penetrance of malignant
R. L. Robinson1, D. Carpenter1, P. J. Halsall1, D. E. Iles2, P. Booms1 2, D. Steele3,
P. M. Hopkins1*† and M.-A. Shaw2†
1MH Investigation Unit, Academic Unit of Anaesthesia, St James’s University Hospital, Leeds LS9 7TF, UK
2Institute of Integrative and Comparative Biology, Faculty of Biological Sciences, L C Miall Building and
3Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds,
Leeds LS2 9JT, UK
*Corresponding author. E-mail: email@example.com
Background. Tissue-specific monoallelic silencing of the RYR1 gene has been proposed as an
explanation for variable penetrance of dominant RYR1 mutations in malignant hyperthermia
(MH). We examined the hypothesis that monoallelic silencing could explain the inheritance of
an MH discordant phenotype in some instances.
Methods. We analysed parent–offspring transmission data from MH kindreds to assess
whether there was any deviation from the expected autosomal dominant Mendelian inheri-
tance pattern. We also evaluated informative single-nucleotide polymorphism (SNP) genotypes
in a cohort of unrelated MH patients using genomic DNA (gDNA, prepared from leucocytes)
and coding DNA (cDNA, prepared from skeletal muscle). Finally, we examined the segregation
of specific mutations at the gDNA and cDNA level within MH families where positive RYR1
gDNA genotype/normal MH phenotype discordance had been observed.
Results. In 2113 transmissions from affected parents, there was a consistent parent-of-origin
effect (P,0.001) with affected fathers having fewer affected daughters (20%, 95% CI 17–22%)
than affected sons (25%, 95% CI 23–26%) or unaffected daughters (27%, 95% CI 25–30%). No
discrepancies were observed between the RYR1 SNP genotypes recorded at the gDNA and
cDNA levels. In 14 MH negative individuals from 11 discordant families, the familial mutation
was detected in skeletal muscle cDNA in all cases.
Conclusions. Epigenetic allele silencing may play a role in the inheritance of MH susceptibility,
but this is unlikely to involve silencing of RYR1.
Br J Anaesth 2009; 103: 220–25
Keywords: calcium channel block; complications, malignant hyperthermia; genetic factors,
hyperthermia; muscle skeletal
Accepted for publication: April 10, 2009
The RYR1 gene on chromosome 19q13.1 encodes the skel-
etal muscle isoform sarcoplasmic reticulum calcium
mutations have been detected in association with malig-
nant hyperthermia (MH) and the rarer congenital myopa-
thies central core disease and multiminicore disease.
Certain RYR1 mutations produce both MH and central
core disease, whereas others result in an MH phenotype
only, a central core disease phenotype only, or in rare
mutations account for the majority of MH cases in the
UK.4RYR1 mutations detected in central core disease
patients are in most cases dominantly inherited, although
there are now several reports of apparently recessive RYR1
mutations in central core disease and multiminicore
Since it was first linked to MH in 1990,10more than
150 missense variants have been identified in RYR1.4In
2001, guidelines for the use of specific RYR1 mutations in
the diagnosis of MH risk were published.11These require
†These authors contributed equally to this work.
# The Author . Published by Oxford University Press on behalf of The Board of Directors of the British Journal of Anaesthesia. All rights reserved.
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British Journal of Anaesthesia 103 (2): 220–25 (2009)
doi:10.1093/bja/aep108 Advance Access publication May 19, 2009
by guest on February 2, 2016
RYR1 is likely to be a rare event and possibly specific to
patients with core myopathy phenotypes.
Thanks to Dr Rupert Quinnell for assistance with statistical analyses.
This work was funded by a grant from the Department of
Health Pharmacogenetics research programme.
1 Curran JL, Hall WJ, Halsall PJ, et al. Segregation of malignant
hyperthermia, central core disease and chromosome 19 markers.
Br J Anaesth 1999; 83: 217–22
2 Monnier N, Romero NB, Lerale J, et al. Familial and sporadic
forms of central core disease are associated with mutations in
the C terminal domain of the skeletal muscle ryanodine receptor.
Hum Mol Genet 2001; 22: 2581–92
3 Shepherd S, Ellis F, Halsall J, Hopkins P. Robinson R. RYR1
mutations in UK central core disease patients: more than just the
C-terminal transmembrane region of the RYR1 gene. J Med Genet
2004; 41: e33
4 Robinson R, Carpenter D, Shaw M-A, Halsall J, Hopkins P.
Mutations in RYR1 in malignant hyperthermia and central core
disease. Hum Mutat 2006; 27: 977–89
5 Ferreiro A, Monnier N, Romero NB, et al. A recessive form of
central core disease, transiently presenting as multiminicore
disease, is associated with a homozygous mutation in the ryano-
dine receptor type 1 gene. Ann Neurol 2002; 51: 750–9
6 Jungbluth H, Muller CR, Halliger-Keller B, et al. Autosomal reces-
sive inheritance of RYR1 mutations in congenital myopathy with
cores. Neurology 2002; 59: 284–7
7 Guis S, Figarella-Branger D, Monnier N, et al. Multiminicore
disease in a family susceptible to malignant hyperthermia: his-
tology, in vitro contracture tests, and genetic characterisation.
Arch Neurol 2004; 61: 106–13
8 Zhou H, Brockington M, Jungbluth H, et al. Epigenetic allele silen-
cing unveils recessive RYR1 mutations in core myopathies. Am J
Hum Genet 2006; 79: 859–68
9 Zhou H, Yamaguchi N, Xu L, et al. Characterization of recessive
RYR1 mutations in core myopathies. Hum Mol Genet 2006; 15:
10 MacLennan DH, Duff C, Zorzato F, et al. Ryanodine receptor
gene is a candidate for predisposition to malignant hyperthermia.
Nature 1990; 343: 559–61
11 Urwyler A, Deufel T, McCarthy T, West S, European Malignant
Hyperthermia Group. Guidelines for molecular detection of sus-
ceptibility to MH. Br J Anaesth 2001; 86: 161–326
12 Robinson RL, Anetseder MJ, Brancadoro V, et al. Recent advance
in the diagnosis of malignant hyperthermia susceptibility: how
confident can we be of genetic testing? Eur J Hum Genet 2003;
13 Robinson RL, Curran JL, Ellis FR, et al. Multiple interacting gene
products may influence susceptibility to malignant hyperthermia.
Ann Hum Genet 2000; 64: 307–20
14 Morison I, Ramsay J, Spencer H. A census of mammalian imprint-
ing. Trends Genet 2005; 21: 466–75
15 Lee M, Hu R, Johnson L, Feinberg A. Human KVLQT gene shows
Wiedemann syndrome chromosomal rearrangements. Nat Genet
1997; 15: 181–5
16 Ørding H, Brancadoro V, Cozzolino S, et al. In vitro contracture
test for diagnosis of malignant hyperthermia following the proto-
col of the European MH Group: results of testing patients surviv-
ing fulminantMH andunrelated
Anaesthesiol Scand 1997; 41: 955–66
17 Monnier N, Kozak-Ribbens G, Krivosic-Horber R, et al.
Correlations between genotype and pharmacological, histological,
functional, and clinical phenotypes in malignant hyperthermia sus-
ceptibility. Hum Mutat 2005; 26: 413–25
18 Ellis FR, Halsall PJ, Christian AS. Clinical presentation of sus-
pected malignant hyperthermia during anaesthesia in 402 pro-
bands. Anaesthesia 1990; 45: 838–41
19 Islander G, Rydenfelt K, Ranklev E, Bodelsson M. Male
hypethermia susceptibility. Acta Anaesthesiol Scand 2007; 51:
20 De Cauwer H, Heytens L, Martin JJ. Workshop report of the
89th ENMC international workshop: central core disease, 19–
20th January 2001, Hilversum, The Netherlands. Neuromuscul
Disord 2002; 12: 588–95
21 Shuaib A, Paasuke RT, Brownell AKW. Central core disease:
clinicalfeatures in 13
low-risk subjects. Acta
patients.Medicine 1987; 66:
Epigenetic allele silencing in MH
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