Relationship between TFAM Gene Polymorphisms and Endurance Capacity in Response to Training

Genetics and sports performance: the present and future in the identification of talent for sports based on DNA testing

The impact of genetics on physiology and sports performance is one of the most debated research aspects in sports sciences. Nearly 200 genetic polymorphisms have been found to influence sports performance traits, and over 20 polymorphisms may condition the status of the elite athlete. However, with the current evidence, it is certainly too early a stage to determine how to use genotyping as a tool for predicting exercise/sports performance or improving current methods of training. Research on this topic presents methodological limitations such as the lack of measurement of valid exercise performance phenotypes that make the study results difficult to interpret. Additionally, many studies present an insufficient cohort of athletes, or their classification as elite is dubious, which may introduce expectancy effects. Finally, the assessment of a progressively higher number of polymorphisms in the studies and the introduction of new analysis tools, such as the total genotype score (TGS) and genome-wide association studies (GWAS), have produced a considerable advance in the power of the analyses and a change from the study of single variants to determine pathways and systems associated with performance. The purpose of the present study was to comprehensively review evidence on the impact of genetics on endurance- and power-based exercise performance to clearly determine the potential utility of genotyping for detecting sports talent, enhancing training, or preventing exercise-related injuries, and to present an overview of recent research that has attempted to correct the methodological issues found in previous investigations.

Candidate Genes of Regulation of Skeletal Muscle Energy Metabolism in Athletes

All biological processes associated with high sports performance, including energy metabolism, are influenced by genetics. DNA sequence variations in such genes, single nucleotide variants (SNVs), could confer genetic advantages that can be exploited to achieve optimal athletic performance. Ignorance of these features can create genetic “barriers” that prevent professional athletes from pursuing a career in sports. Predictive Genomic DNA Profiling reveals single nucleotide variations (SNV) that may be associated with better suitability for endurance, strength and speed sports. (1) Background: To conduct a research on candidate genes associated with regulation of skeletal muscle energy metabolism among athletes. (2) Methods: We have searched for articles in SCOPUS, Web of Science, Google Scholar, Clinical keys, PubMed, e-LIBRARY databases for the period of 2010–2020 using keywords and keywords combinations; (4) Conclusions: Identification of genetic markers associated with the regulation of energy metabolism in skeletal muscles can help sports physicians and coaches develop personalized strategies for selecting children, teenagers and young adults for endurance, strength and speed sports (such as jogging, middle or long distance runs). However, the multifactorial aspect of sport performances, including impact of genetics, epigenetics, environment (training and etc.), is important for personalized strategies for selecting of athletes. This approach could improve sports performance and reduce the risk of sports injuries to the musculoskeletal system.

Genes to predict VO2max trainability: a systematic review

Background

Cardiorespiratory fitness (VO_2max) is an excellent predictor of chronic disease morbidity and mortality risk. Guidelines recommend individuals undertake exercise training to improve VO_2max for chronic disease reduction. However, there are large inter-individual differences between exercise training responses. This systematic review is aimed at identifying genetic variants that are associated with VO_2max trainability.

Methods

Peer-reviewed research papers published up until October 2016 from four databases were examined. Articles were included if they examined genetic variants, incorporated a supervised aerobic exercise intervention; and measured VO_2max/VO_2peak pre and post-intervention.

Results

Thirty-five articles describing 15 cohorts met the criteria for inclusion. The majority of studies used a cross-sectional retrospective design. Thirty-two studies researched candidate genes, two used Genome-Wide Association Studies (GWAS), and one examined mRNA gene expression data, in addition to a GWAS. Across these studies, 97 genes to predict VO_2max trainability were identified. Studies found phenotype to be dependent on several of these genotypes/variants, with higher responders to exercise training having more positive response alleles than lower responders (greater gene predictor score). Only 13 genetic variants were reproduced by more than two authors. Several other limitations were noted throughout these studies, including the robustness of significance for identified variants, small sample sizes, limited cohorts focused primarily on Caucasian populations, and minimal baseline data. These factors, along with differences in exercise training programs, diet and other environmental gene expression mediators, likely influence the ideal traits for VO_2max trainability.

Conclusion

Ninety-seven genes have been identified as possible predictors of VO_2max trainability. To verify the strength of these findings and to identify if there are more genetic variants and/or mediators, further tightly-controlled studies that measure a range of biomarkers across ethnicities are required.

Mitochondriogenesis genes and extreme longevity

Genes of the proliferator-activated receptor delta (PPARD)-peroxisome proliferator-activated receptor γ coactivator 1α (PPARGC1A, also termed PGC1-α)-nuclear respiratory factor (NRF)-mitochondrial transcription Factor A (TFAM) mitochondriogenesis pathway can influence health/disease phenotypes, yet their association with extreme longevity is not known. We studied the association of five common polymorphisms in genes of this pathway (rs2267668, rs8192678, rs6949152, rs12594956, rs1937) and extreme longevity using a case (107 centenarians)-control (284 young adults) design. We found no between-group differences in allele/genotype frequencies, except for CC genotype in rs1937 (p=0.003), with no representation in controls (0%), versus 2.8% in centenarians (2 men, 1 woman). In summary, the studied genetic variants of the PPARD-PPARGC1A-NRF-TFAM pathway were not associated with extreme longevity, yet a marginal association could exist for rs1937.

Mitochondrial biogenesis related endurance genotype score and sports performance in athletes

We determined the probability of individuals having the 'optimal' mitochondrial biogenesis related endurance polygenic profile, and compared the endurance polygenic profile of Israeli (Caucasian) endurance athletes (n = 74), power athletes (n = 81), and non-athletes (n = 240). We computed a mitochondrial biogenesis related 'endurance genotype score' (EGS, scoring from 0 to 100) from the accumulated combination of six polymorphisms in the PPARGC1A-NRF-TFAM pathway. Some of the variant alleles of the polymorphisms studied were so infrequent, that the probability of possessing an 'optimal' EGS (= 100) was 0% in the entire study population. However, the EGS was significantly higher (P<0.001) in endurance athletes (38.9 ± 17.1) compared with controls (30.6 ± 12.4) or power athletes (29.0 ± 11.2). In summary, although the probability of an individual possessing a theoretically 'optimal' genetic background for endurance sports is very low, in general endurance athletes have a polygenic profile that is more suitable for mitochondrial biogenesis.

The human gene map for performance and health-related fitness phenotypes: the 2006-2007 update

This update of the human gene map for physical performance and health-related fitness phenotypes covers the research advances reported in 2006 and 2007. The genes and markers with evidence of association or linkage with a performance or a fitness phenotype in sedentary or active people, in responses to acute exercise, or for training-induced adaptations are positioned on the map of all autosomes and sex chromosomes. Negative studies are reviewed, but a gene or a locus must be supported by at least one positive study before being inserted on the map. A brief discussion on the nature of the evidence and on what to look for in assessing human genetic studies of relevance to fitness and performance is offered in the introduction, followed by a review of all studies published in 2006 and 2007. The findings from these new studies are added to the appropriate tables that are designed to serve as the cumulative summary of all publications with positive genetic associations available to date for a given phenotype and study design. The fitness and performance map now includes 214 autosomal gene entries and quantitative trait loci plus seven others on the X chromosome. Moreover, there are 18 mitochondrial genes that have been shown to influence fitness and performance phenotypes. Thus,the map is growing in complexity. Although the map is exhaustive for currently published accounts of genes and exercise associations and linkages, there are undoubtedly many more gene-exercise interaction effects that have not even been considered thus far. Finally, it should be appreciated that most studies reported to date are based on small sample sizes and cannot therefore provide definitive evidence that DNA sequence variants in a given gene are reliably associated with human variation in fitness and performance traits.