BabyScreen+ newborn screening

Gene: RYR1

Green List (high evidence)

Well established association with susceptibility to malignant hyperthermia.

However, variants in this gene also cause a range of muscular phenotypes, for which there is no specific treatment.

Association with malignant hyperthermia is rated 'strongly actionable' in children by ClinGen.

MH susceptibility (MHS) is a pharmacogenetic skeletal muscle disorder where exposure to certain volatile anesthetics (i.e., desflurane, enflurane, halothane, isoflurane, sevoflurane), either alone or with a depolarizing muscle relaxant (succinylcholine), may trigger uncontrolled skeletal muscle hypermetabolism. An MH episode may begin with hypercapnia, rapidly rising end-tidal CO2, and tachycardia followed by hyperthermia. Additional symptoms may include acidosis, muscle rigidity, compartment syndrome, rhabdomyolysis and subsequent increased creatine kinase, hyperkalemia with a risk for cardiac arrhythmia or even arrest, and myoglobinuria with a risk for renal failure.

There is mounting evidence that some individuals with MHS may also develop episodes triggered by non-anesthetic conditions such as heat and/or exercise. These non-anesthetic-induced episodes, often called MH-like syndrome, may manifest as exertional rhabdomyolysis (ER).

Surgical management recommendations include preparation of the anesthesia workstation to reduce or prevent exposure to triggering anesthetics (e.g., remove vaporizers from machine and replace all disposables), vigilant monitoring for signs and symptoms of MH during perioperative period, and close observation and monitoring postoperatively.

MHS patients should carry identification of their susceptibility and inform those responsible for their care of their MH status.

Do not use the following MH triggering drugs for MHS patients: inhaled general anesthetics (desflurane, enflurane, halothane, isoflurane, sevoflurane) and depolarizing muscle relaxants (succinylcholine).

Created: 13 Dec 2022, 7:58 a.m. | Last Modified: 14 Dec 2022, 5:44 a.m.

Panel Version: 0.1425

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
{Malignant hyperthermia susceptibility 1} MIM#145600