Introduction The myostatin (MSTN) gene controls skeletal muscle mass by negatively regulating growth of skeletal muscle. Mutations in MSTN leading to inactive or defective gene product have been shown to double skeletal muscle mass in mice, cows, dogs and sheep. Functional MSTN mutations are very rare in humans. A number of polymorphisms in MSTN have been investigated for their associations with physical performance phenotype, however overall findings have been inconsistent. As the functionality of the reported MSTN polymorphisms is uncertain, we analysed the whole loci of MSTN gene. We hypothesised that variants of the MSTN might be associated with endurance or strength/power performance of Lithuanian elite athletes.
Methods The study involved 235 Lithuanian elite athletes (endurance-oriented athletes (n = 79), power-oriented athletes (n = 120) and athletes with mixed endurance/power activity (n = 36)) and 200 controls (non-athlete, healthy, Lithuanian citizens). Anthropometric measurements, anaerobic muscle strength (handgrip, counter-movement jump and stair climbing tests) and VO2max were evaluated. Genomic DNA was extracted from blood leukocytes by phenol-chloroform method. The coding regions and surrounding sequences of the MSTN gene were analysed using automatized Sanger sequencing technique.
Results After having performed the sequencing of the MSTN gene, we identified two following genetic variants: (1) the deletion of one of three adenines in the first intron (c.373 + 90 delA, rs11333578) and the SNP in the second exon (c.458A>G, p.Lys(K)153Arg(R), rs1805086). From the dbSNP and the HapMap databases and previous publications, the polymorphisms in MSTN have been found in variety of ethnic populations. The functional relevance of the (c.373 + 90 delA) polymorphism has not yet been published and MAF of this polymorphism in our study was similar with findings of the European population. The polymorphism in the second exon (Lys153Arg) and the homozygous genotype Arg/Arg was present only in one elite canoe rower athlete and only 2 controls showed heterozygous Lys/Arg genotype. The Lys allele was the most common form in athletes and control groups. Surprisingly, the intronic variant (c.373 + 90 delA) was abundant among all investigated samples. Homozygous for wild-type allele (A/A), heterozygous for deletion (A/-) and homozygous for deletion (-/-) genotypes were in Hardy–Weinberg equilibrium (P > 0.05). Genotype frequencies were significantly different between the total athlete group and the controls (A/A 57.4%; A/- 34.9%; -/- 7.7% vs. A/A 64%; A/- 34.5%; -/- 1.5%; P = 0.01). Endurance athletes (A/A 54.4%; A/- 35.4%; -/- 10.1%) and “mixed” athletes (A/A 55.6%; A/- 30.6%; -/- 13.9%) had significantly different genotypes compared to controls (P = 0.003 and P = 0.0008 respectively). There was a significantly higher deletion allele frequency in endurance (27.8%) and “mixed” (29.2%) groups compared to controls (18.7%, p < 0.05). For all that we did not determine statistical significant differences between MSTN (c.373 + 90 delA) genotypes and physical performance phenotypes (muscle mass, anaerobic muscle strength and VO2max).
Conclusions From a functional point of view, the MSTN gene appears to be feasible candidate for physical performance trait. However, we found no significant association between MSTN genotypes and phenotype. The polymorphism in the second exon of the MSTN gene (Lys153Arg) was found only in one high-level canoe rower athlete. As there are substantial differences in allele frequencies of the SNP among different ethnic populations, it is quite possible that this variant contributes to physical performance in athletes. The previously unnoticed (c.373 + 90 delA) polymorphism amidst the intron 1 was significantly associated with endurance performance status in Lithuanian elite athletes. Our data, for the first time, suggest a strong role of MSTN (c.373 + 90 delA) in determining sport success. Further research of larger groups would be required to obtain more accurate results.
- physical performance
- myostatin gene
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