title: Genetic variation in RYR1 and malignant hyperthermia phenotypes.
abstract: BACKGROUND
  Malignant hyperthermia (MH) is associated, in the majority of cases, with mutations in RYR1, the gene encoding the skeletal muscle ryanodine receptor. Our primary aim was to assess whether different RYR1 variants are associated with quantitative differences in MH phenotype.
  
  
  METHODS
  The degree of in vitro pharmacological muscle contracture response and the baseline serum creatine kinase (CK) concentration were used to generate a series of quantitative phenotypes for MH. We then undertook the most extensive RYR1 genotype-phenotype correlation in MH to date using 504 individuals from 204 MH families and 23 RYR1 variants. We also determined the association between a clinical phenotype and both the laboratory phenotype and RYR1 genotype.
  
  
  RESULTS
  We report a novel correlation between the degree of in vitro pharmacological muscle contracture responses and the onset time of the clinical MH response in index cases (P<0.05). There was also a significant correlation between baseline CK concentration and clinical onset time (P=0.039). The specific RYR1 variant was a significant determinant of the severity of each laboratory phenotype (P<0.0001).
  
  
  CONCLUSIONS
  The MH phenotype differs significantly with different RYR1 variants. Variants leading to more severe MH phenotype are distributed throughout the gene and tend to lie at relatively conserved sites in the protein. Differences in phenotype severity between RYR1 variants may explain the variability in clinical penetrance of MH during anaesthesia and why some variants have been associated with exercise-induced rhabdomyolysis and heat stroke. They may also inform a mutation screening strategy in cases of idiopathic hyperCKaemia.
authors: MH Investigation Unit, Academic Unit Anaesthesia, St James's University Hospital, Leeds LS9 7TF, UK.
authors: D
authors: D
authors: Carpenter
authors: R L
authors: RL
authors: Robinson
authors: R J
authors: RJ
authors: Quinnell
authors: C
authors: C
authors: Ringrose
authors: M
authors: M
authors: Hogg
authors: F
authors: F
authors: Casson
authors: P
authors: P
authors: Booms
authors: D E
authors: DE
authors: Iles
authors: P J
authors: PJ
authors: Halsall
authors: D S
authors: DS
authors: Steele
authors: M-A
authors: MA
authors: Shaw
authors: P M
authors: PM
authors: Hopkins
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D003402:Creatine Kinase / Q000097:blood; D004252:DNA Mutational Analysis / Q000379:methods; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006221:Halothane / Q000494:pharmacology; D006801:Humans; D008297:Male; D008305:Malignant Hyperthermia / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology; D009119:Muscle Contraction / Q000187:drug effects; D009154:Mutation; D010641:Phenotype; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics*; D046509:Tissue Culture Techniques
chemical_list: D018685:Anesthetics, Inhalation; D018076:DNA, Complementary; D010726:Phosphodiesterase Inhibitors; D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D003402:Creatine Kinase; D006221:Halothane