Polymorphisms in the IGF1 signalling pathway including the myostatin gene are associated with left ventricular mass in male athletes.
BACKGROUND
Athlete's heart as an adaptation to long-time and intensive endurance training can vary considerably between individuals. Genetic polymorphisms in the cardiological relevant insulin-like growth factor 1 (IGF1) signalling pathway seem to have an essential influence on the extent of physiological hypertrophy.


OBJECTIVE
Analysis of polymorphisms in the genes of IGF1, IGF1 receptor (IGF1R) and the negative regulator of the cardiac IGF1 signalling pathway, myostatin (MSTN), and their relation to left ventricular mass (LVM) of endurance athletes.


METHODS
In 110 elite endurance athletes or athletes with a high amount of endurance training (75 males and 35 females) and 27 male controls, which were examined by echocardiographic imaging methods and ergometric exercise-testing, the genotypes of a cytosine-adenine repeat polymorphism in the promoter region of the IGF1 gene and a G/A substitution at position 3174 in the IGF1R gene were determined. Additionally, a mutation screen of the MSTN gene was performed.


RESULTS
The polymorphisms in the IGF1 and the IGF1R gene showed a significant relation to the LVM for male (IGF1: p=0.003; IGF1R: p=0.01), but not for female athletes. The same applies to a previously unnoticed polymorphism in the 1 intron of the MSTN gene, whose deletion allele (AAA→AA) appears to increase the myostatic effect (p=0.015). Moreover, combinations of the polymorphisms showed significant synergistic effects on the LVM of the male athletes.


CONCLUSIONS
The authors' results argue for the importance of polymorphisms in the IGF1 signalling pathway in combination with MSTN on the variant degree of physiological hypertrophy of male athletes.
Karlowatz
Ruth-Jessica
RJ
Institute of Human Genetics, University of Saarland/IGD Saar GmbH, Homburg/Saar, Germany.
Scharhag
Jürgen
J
Rahnenführer
Jörg
J
Schneider
Ulrich
U
Jakob
Ernst
E
Kindermann
Wilfried
W
Zang
Klaus Dieter
KD
D000328:Adult; D003430:Cross-Sectional Studies; D004452:Echocardiography; D005260:Female; D005838:Genotype; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008297:Male; D055435:Myostatin / Q000235:genetics*; D017354:Point Mutation / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics*; D017526:Receptor, IGF Type 1 / Q000235:genetics*; D013177:Sports; D055815:Young Adult
D055435:Myostatin; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1