title: Exome sequencing reveals novel rare variants in the ryanodine receptor and calcium channel genes in malignant hyperthermia families.
abstract: BACKGROUND
  About half of malignant hyperthermia (MH) cases are associated with skeletal muscle ryanodine receptor 1 (RYR1) and calcium channel, voltage-dependent, L type, α1S subunit (CACNA1S) gene mutations, leaving many with an unknown cause. The authors chose to apply a sequencing approach to uncover causal variants in unknown cases. Sequencing the exome, the protein-coding region of the genome, has power at low sample sizes and identified the cause of over a dozen Mendelian disorders.
  
  
  METHODS
  The authors considered four families with multiple MH cases lacking mutations in RYR1 and CACNA1S by Sanger sequencing of complementary DNA. Exome sequencing in two affecteds per family, chosen for maximum genetic distance, were compared. Variants were ranked by allele frequency, protein change, and measures of conservation among mammals to assess likelihood of causation. Finally, putative pathogenic mutations were genotyped in other family members to verify cosegregation with MH.
  
  
  RESULTS
  Exome sequencing revealed one rare RYR1 nonsynonymous variant in each of three families (Asp1056His, Val2627Met, Val4234Leu), and one CACNA1S variant (Thr1009Lys) in the fourth family. These were not seen in variant databases or in our control population sample of 5,379 exomes. Follow-up sequencing in other family members verified cosegregation of alleles with MH.
  
  
  CONCLUSIONS
  The authors found that using both exome sequencing and allele frequency data from large sequencing efforts may aid genetic diagnosis of MH. In a sample selected by the authors, this technique was more sensitive for variant detection in known genes than Sanger sequencing of complementary DNA, and allows for the possibility of novel gene discovery.
authors.affiliation: * Assistant Professor, Department of Anesthesiology and Pain Medicine, † Professor, ‡ Associate Professor, § Biostatistician, Department of Medicine, Division of Medical Genetics, ‖ Graduate Student, # Research Professor, ** Research Scientist, †† Professor, Department of Genome Sciences, University of Washington, Seattle, Washington. ‡‡ Research Scientist, §§ Professor, Leeds Institute of Molecular Medicine, Leeds, United Kingdom.
authors.forename: Jerry H
authors.initials: JH
authors.lastname: Kim
authors.forename: Gail P
authors.initials: GP
authors.lastname: Jarvik
authors.forename: Brian L
authors.initials: BL
authors.lastname: Browning
authors.forename: Ramakrishnan
authors.initials: R
authors.lastname: Rajagopalan
authors.forename: Adam S
authors.initials: AS
authors.lastname: Gordon
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Rieder
authors.forename: Peggy D
authors.initials: PD
authors.lastname: Robertson
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Nickerson
authors.forename: Nickla A
authors.initials: NA
authors.lastname: Fisher
authors.forename: Philip M
authors.initials: PM
authors.lastname: Hopkins
mesh_terms: D000465:Algorithms; D015220:Calcium Channels / Q000235:genetics*; D020746:Calcium Channels, L-Type; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D030541:Databases, Genetic; D059472:Exome / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005500:Follow-Up Studies; D006801:Humans; D008126:Lod Score; D008305:Malignant Hyperthermia / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics*
chemical_list: C412223:CACNA1S protein, human; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D018076:DNA, Complementary; D019837:Ryanodine Receptor Calcium Release Channel