acute MH events will ultimately prove fatal. This
estimate isn't accurate based on calls to the MHAUS
hotline. Professionals who man the hotline are
alerted to one to two likely cases of MH per week.
But we're also aware of only one to two deaths
from MH every couple years. Those numbers are
likely underestimates because of
the cases that we're unaware of,
but at most the mortality is likely
less than 2%. This is good news. It
means that the combination of
MH awareness among surgical
teams and the success of treat-
ment with dantrolene can reliably
reduce MH mortality to histori-
cally low numbers. In the future,
when whole exome screening
becomes more cost effective and
all patients are screened for MH
causative variants before surgery,
the incidence of MH events will
be close to zero. There will, how-
ever, continue to be rare reac-
tions in patients with previously
unknown pathogenic variants.
MYTH #7:
MH susceptibility is
associated with Duchenne and
Becker muscular dystrophy
FACT: Many clinicians fear hypo-
tonic patients are at risk for MH
susceptibility. Almost all MH sus-
ceptibility is conferred by inheri-
tance of a pathogenic variant on
the RYR1 gene located on chro-
mosome 19 (very rare cases of
MH susceptibility are associated
with pathogenic variants of the
CACNA1S and STAC3 genes).
These ryanodinopathies consist
mainly of the phenotypes previ-
ously described as central core
disease, multiminicore disease
and King-Denborough syndrome.
The myth, however, stems
from the belief that sudden or
delayed rhabdomyolysis associated with the admin-
istration of triggering agents represents MH. This
reaction — while having some features in common
with MH — actually represents muscle breakdown
in certain susceptible patients, as opposed to the
predominantly hypermetabolic MH reaction. For
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