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Androgen receptor gene polymorphisms lean mass and performance in young men
Amelia Guadalupe-Grau1, F Germán Rodríguez-González, Cecilia Dorado
1Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafi ra s/n, Las Palmas de Gran Canaria, 35017, Spain.
British Journal of Sports Medicine
|July 21, 2009
Summary
Androgen receptor (AR) gene polymorphisms, specifically CAG and GGN repeats, were studied for their effect on muscle mass and strength. The study found no significant impact of these AR gene variations on lean body mass or overall fitness in young men.
Area of Science:
- Genetics and Molecular Biology
- Exercise Physiology
- Human Performance
Background:
- The androgen receptor (AR) gene contains repeat length polymorphisms, specifically CAG (polyglutamine) and GGN (polyglycine) repeats in exon 1.
- Variations in these repeat lengths can influence AR protein levels and transcriptional activity, potentially affecting androgen signaling.
- Shorter CAG and GGN repeats are associated with stronger androgen signaling, while longer repeats are linked to weaker signaling.
Purpose of the Study:
- To investigate the hypothesis that CAG and GGN repeat polymorphisms in the androgen receptor (AR) gene influence muscle mass and muscular strength phenotype traits.
- To determine if specific lengths of CAG and GGN repeats correlate with differences in lean body mass and various fitness parameters in men.
Main Methods:
- Genotyping of 282 men (mean age 28.6 years) for CAG and GGN repeat lengths in the AR gene.
- Polymerase Chain Reaction (PCR) and fragment analysis were used for repeat length determination.
- DNA sequencing confirmed results in selected samples; individuals were categorized into 'short' and 'long' repeat groups based on defined thresholds.
Main Results:
- No statistically significant differences in lean body mass or fitness levels were observed between groups with short (≤21) versus long (>21) CAG repeats.
- Similarly, no significant differences were found between groups with short (≤23) versus long (>23) GGN repeats.
- A non-significant trend (r=-0.11, p=0.06) suggested a potential correlation between GGN repeat length and lean mass in the extremities.
Conclusions:
- The lengths of CAG and GGN repeats within the androgen receptor gene do not appear to significantly influence overall lean mass or fitness levels in young men.
- While a trend was observed for GGN repeats and extremity lean mass, further research is needed to confirm any potential association.
- These findings suggest that other genetic or environmental factors may play a more dominant role in determining muscle mass and strength phenotypes.
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