title: Can IGF-I polymorphism affect power and endurance athletic performance?
abstract: OBJECTIVE
  Insulin-like growth factor-I (IGF-I) plays a key role in exercise-associated muscle growth and development. The regulatory region of the promoter of the IGF-I gene is labile, but changes in this region were studied mostly in the elderly and in relation to pathological states. C-1245T (rs35767) is a genetic variation in the promoter region of the IGF-I gene. The minor allele T was found to be associated with higher circulating IGF-I levels, and possibly with increased muscle mass. The aim of the current study was to analyze the frequency distribution of C-1245T SNP in athletic and nonathletic Israeli populations.
  
  
  METHODS
  One hundred and sixty-five athletes (78 endurance-type athletes, and 87 power-type athletes) and 159 nonathletic healthy individuals participated in the current study. Genomic DNA was extracted from peripheral EDTA treated anti-coagulated blood using a standard protocol. Genotyping of the IGF1 C-1245T polymorphism was performed using polymerase chain reaction (PCR).
  
  
  RESULTS
  We found that the endurance and power athletes' allele and genotype frequencies were significantly different from those of the control group. Only 4.8% of the athletes were TT carriers, but none of the controls carried this genotype. The T allele was found to be more frequent in the top-level power athletes (international and Olympic level) compared to national level athletes, but such a difference was not found in endurance athletes.
  
  
  CONCLUSIONS
  Our findings suggest a possible contribution for the relatively rare IGF-I TT genotype to endurance performance, and in particular to power sport excellence in Israeli athletes.
authors.affiliation: The Zinman College of Physical Education and Sports Sciences at the Wingate Institute, Genetics and Molecular Biology Laboratory, Netanya 42902, Israel.
authors.forename: Sigal
authors.initials: S
authors.lastname: Ben-Zaken
authors.forename: Yoav
authors.initials: Y
authors.lastname: Meckel
authors.forename: Dan
authors.initials: D
authors.lastname: Nemet
authors.forename: Alon
authors.initials: A
authors.lastname: Eliakim
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007557:Israel; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000235:genetics*; D010807:Physical Endurance / Q000235:genetics*; D011110:Polymorphism, Genetic; D044465:White People / Q000235:genetics; D055815:Young Adult
chemical_list: D007334:Insulin-Like Growth Factor I
keywords: Athletic performance; Endurance athletes; Genetic polymorphism; IGF1; Power athletes