title: Genetic predisposition scores associate with muscular strength, size, and trainability.
abstract: BACKGROUND
  The number of studies trying to identify genetic sequence variation related to muscular phenotypes has increased enormously. The aim of this study was to identify the role of a genetic predisposition score (GPS) based on earlier identified gene variants for different muscular endophenotypes to explain the individual differences in muscular fitness characteristics and the response to training in patients with coronary artery disease.
  
  
  METHODS
  Two hundred and sixty coronary artery disease patients followed a standard ambulatory, 3-month supervised training program for cardiac patients. Maximal knee extension strength (KES) and rectus femoris diameter were measured at baseline and after rehabilitation. Sixty-five single nucleotide polymorphisms (SNP) in 30 genes were selected based on genotype-phenotype association literature. Backward regression analysis revealed subsets of SNP associated with the different phenotypes. GPS were constructed for all sets of SNP by adding up the strength-increasing alleles. General linear models and multiple stepwise regression analysis were used to test the explained variance of the GPS in baseline and strength responses. Receiver operating characteristic curve analyses were performed to discriminate between high- and low-responder status.
  
  
  RESULTS
  GPS were significantly associated with the rectus femoris diameter (P < 0.01) and its response (P < 0.0001), the isometric KES (P < 0.05) and its response (P < 0.01), the isokinetic KES at 60° · s (P < 0.05) and 180° · s (P < 0.001) and their responses to training (P < 0.0001), and the isokinetic KES endurance (P < 0.001) and its change after training (P < 0.0001). The GPS was shown as an independent determinant in baseline and response phenotypes with partial explained variance up to 23%. Receiver operating characteristic analysis showed a significant discriminating accuracy of the models, including the GPS for responses to training, with areas under the curve ranging from 0.62 to 0.85.
  
  
  CONCLUSIONS
  GPS for muscular phenotypes showed to be associated with baseline KES, muscle diameter, and the response to training in cardiac rehabilitation patients.
authors: Research Group for Cardiovascular and Respiratory Rehabilitation, Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors: Tom
authors: T
authors: Thomaes
authors: Martine
authors: M
authors: Thomis
authors: Steven
authors: S
authors: Onkelinx
authors: Kaatje
authors: K
authors: Goetschalckx
authors: Robert
authors: R
authors: Fagard
authors: Diether
authors: D
authors: Lambrechts
authors: Luc
authors: L
authors: Vanhees
mesh_terms: D000368:Aged; D003324:Coronary Artery Disease / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000235:genetics* / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010641:Phenotype; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D012044:Regression Analysis