title: Polymorphisms in PTK2 are associated with skeletal muscle specific force: an independent replication study.
abstract: OBJECTIVE
  The aim of the study was to investigate two single nucleotide polymorphisms (SNP) in PTK2 for associations with human muscle strength phenotypes in healthy men.
  
  
  METHODS
  Measurement of maximal isometric voluntary knee extension (MVCKE) torque, net MVCKEtorque and vastus lateralis (VL) specific force, using established techniques, was completed on 120 Caucasian men (age = 20.6 ± 2.3 year; height = 1.79 ± 0.06 m; mass = 75.0 ± 10.0 kg; mean ± SD). All participants provided either a blood (n = 96) or buccal cell sample, from which DNA was isolated and genotyped for the PTK2 rs7843014 A/C and rs7460 A/T SNPs using real-time polymerase chain reaction.
  
  
  RESULTS
  Genotype frequencies for both SNPs were in Hardy-Weinberg equilibrium (X2≤ 1.661, P ≥ 0.436). VL specific force was 8.3% higher in rs7843014 AA homozygotes than C-allele carriers (P = 0.017) and 5.4% higher in rs7460 AA homozygotes than T-allele carriers (P = 0.029). No associations between either SNP and net MVCKEtorque (P ≥ 0.094) or peak MVCKEtorque (P ≥ 0.107) were observed.
  
  
  CONCLUSIONS
  These findings identify a genetic contribution to the inter-individual variability within muscle specific force and provides the first independent replication, in a larger Caucasian cohort, of an association between these PTK2 SNPs and muscle specific force, thus extending our understanding of the influence of genetic variation on the intrinsic strength of muscle.
authors.affiliation: MMU Sports Genomics Laboratory, Department of Exercise and Sport Science, Manchester Metropolitan University, Crewe, UK. g.stebbings@mmu.ac.uk.
authors.forename: Georgina K
authors.initials: GK
authors.lastname: Stebbings
authors.affiliation: MMU Sports Genomics Laboratory, Department of Exercise and Sport Science, Manchester Metropolitan University, Crewe, UK.|Institute of Sport, Exercise and Health, University College London, London, UK.
authors.forename: A G
authors.initials: AG
authors.lastname: Williams
authors.affiliation: MMU Sports Genomics Laboratory, Department of Exercise and Sport Science, Manchester Metropolitan University, Crewe, UK.
authors.forename: C I
authors.initials: CI
authors.lastname: Morse
authors.affiliation: MMU Sports Genomics Laboratory, Department of Exercise and Sport Science, Manchester Metropolitan University, Crewe, UK.
authors.forename: S H
authors.initials: SH
authors.lastname: Day
mesh_terms: D000293:Adolescent; D051417:Focal Adhesion Kinase 1 / Q000235:genetics*; D005787:Gene Frequency; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000235:genetics*; D018482:Muscle, Skeletal / Q000502:physiology; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D055815:Young Adult
chemical_list: D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human
keywords: Focal adhesion kinase; Genetic polymorphism; Lateral transmission; Muscle quality; Protein tyrosine kinase 2; Vastus lateralis