PPARGC1A genotype (Gly482Ser) predicts exceptional endurance capacity in European men

[Review of genetic research and testing in sport]

There is compelling evidence for a genetic contribution to physical performance. In addition, there is an advanced scientific knowledge on the predisposition to sports-related diseases and injuries. Genetic testing of performance related polymorphisms can serve as a new opportunity for developing the process of talent selection. Sport-related genetic information may also allow for individualization of the training and improve performance. Genetic testing may also play an important role in the pre-participation screening for injuries and disease risks.

ACE I/D, ACTN3 R577X, PPARD T294C and PPARGC1A Gly482Ser polymorphisms and physical fitness in Taiwanese late adolescent girls

Physical performance of youth is influenced by various factors, including body composition, biological maturity status, level of habitual physical activity, and muscular strength. Muscular strength has been largely attributed to genetic effects. To exclude possible confounding effects from various acquired factors, this study examined the relationships between polymorphisms of the angiotensin-converting enzyme (ACE), α-actinin-3 (ACTN3), peroxisome proliferator-activated receptor delta (PPARD), and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PPARGC1A) genes and performance as measured by six fitness tests (handgrip strength of dominant hand, 30- and 60-s sit-ups, standing long jump, 60-m dash, and 800-m run) in 170 sedentary adolescent girls with the adjustment of anthropometric characteristics. We found that subjects with the ACE DD genotype were significantly heavier than those with I allele, while those with the ACTN3 RR genotype had higher fat-free mass percentage (FFM%) than those with the XX genotype. In addition, those with the PPARD TT genotype were significantly taller, heavier, and had a greater FFM than those with the CC genotype. Subjects with the ACE DD, ACTN3 RR and PPARD TC genotype had better performance in handgrip strength, 30- and 60-s sit-up tests, and standing long jump, respectively, when individual gene was analyzed independently after adjusting anthropometric characteristics. In the gene combination analysis, subjects with ACE DD, ACTN3 RR and PPARD TT genotype had significantly greater performance in handgrip strength. Overall, the results indicate that the genes studied have a modest influence on individual performance as assessed by specific fitness and strength tests in female late adolescents.

The PPARGC1A gene Gly482Ser in Polish and Russian athletes

Peroxysome proliferator-activated receptor gamma coactivator-1-alpha (PGC-1α; encoded by the gene PPARGC1A in humans) is a crucial component in training-induced muscle adaptation because it is a co-activator of transcriptional factors that control gene expression in coordinated response to exercise. It has been suggested that a Gly482Ser substitution in PPARGC1A has functional relevance in the context of human disorders and athletic performance. To test this hypothesis, we examined the genotype distribution of PPARGC1A Gly482Ser in a group of Polish athletes and confirmed the results obtained in a replication study of Russian athletes. We found that the 482Ser allele was under-represented in the cohort of Polish and Russian athletes examined compared with unfit controls (P < 0.0001). A statistically significant low frequency of the 482Ser allele was observed among the endurance,strength-endurance, and sprint-strength groups of Polish athletes (P = 0.019, P = 0.022, and P < 0.0001, respectively). The replication study revealed that the 482Ser allele was also less prevalent in Russian endurance and strength-endurance athletes (P = 0.029 and P < 0.0001, respectively). Our results suggest that the PPARGC1A Gly482Ser polymorphism is associated with elite endurance athletic status. These findings support the hypothesis that the PPARGC1A 482Ser allele may impair aerobic capacity: thus, the Gly482 allele may be considered a beneficial factor for endurance performance.

PGC1α gene Gly482Ser polymorphism predicts improved metabolic, inflammatory and vascular outcomes following bariatric surgery

AIMS/HYPOTHESIS

Bariatric surgery is currently employed as an effective approach to treat class III obesity and class II obesity with co-morbidities. Unfortunately, the general anthropometric and metabolic outcomes of the surgery are not homogeneous, and defining the eligibility criteria that allow for a more precise prediction of the outcomes of this invasive procedure will refine the selection of patients. Here we tested the hypothesis that the Gly482Ser polymorphism of the ppargc1a gene would predict different outcomes following bariatric surgery.

METHODS

Fifty-five patients (26 Gly/Gly and 29 Gly/Ser+Ser/Ser) selected for the Roux-en-Y gastric bypass according to the National Institutes of Health Consensus Statement criteria were followed up for 1 year, monitoring their anthropometric, metabolic and inflammatory parameters.

RESULTS

Patients with the Gly482Ser polymorphism had significantly improved reductions in the waist/hip ratio, fasting blood glucose, C-reactive protein, blood leukocyte count, serum interleukin-6 and intima-media thickness of the carotid artery, as compared with Gly/Gly patients.

CONCLUSIONS/INTERPRETATION

Thus, the Gly482Ser polymorphism may predict a more favorable metabolic and inflammatory outcome for obese patients submitted to bariatric surgery, leading to a reduced atherosclerotic risk.

Exercise and the treatment of diabetes and obesity

An active lifestyle increases general health and is protects from a number of different conditions, including exercise and obesity. There is emerging evidence that exercise by itself exerts clinically beneficial effects in both lean and obese subjects, even in the absence of effects on weight.1 Recent results have brought an increasing understanding of the molecular mechanisms underlying the beneficial effects of exercise at the level of metabolism and changes in gene expression. There is a significant dose-response to the effect of exercise, and the current guidelines regarding exercise amount may need to be revised upwards. Furthermore, this treatment option should not be overlooked.

The champions' mitochondria: is it genetically determined? A review on mitochondrial DNA and elite athletic performance

Aerobic ATP generation by the mitochondrial respiratory oxidative phosphorylation system (OXPHOS) is a vital metabolic process for endurance exercise. Notably, mitochondrial DNA (mtDNA) codifies 13 of the 83 polypeptides implied in the respiratory chain. As such, there is a strong rationale for identifying an association between mtDNA variants and “aerobic” (endurance) exercise phenotypes. The aim of this review is to summarize current knowledge on the association between mtDNA, nuclear genes involved in mitochondriogenesis, and elite endurance athletic status. Several studies in nonathletic people have demonstrated an association between certain mtDNA lineages and aerobic performance, characterized by maximal oxygen uptake (V̇o2max). Whether mtDNA haplogroups are also associated with the status of being an elite endurance athlete is more controversial, with differences between studies arising from the different ethnic backgrounds of the athletic cohorts (Caucasian of mixed geographic origin, Asiatic, or East African).

Physiological variables and mitochondrial-related genotypes of an athlete who excels in both short and long-distance running

We report the athletic, physiological and mitochondrial-related genomic data of an Israeli endurance runner. He is holding the Israeli record in 10,000, 5000, 1500 and 800 m run, along with being one of the best Israeli 400 m runners. We tested the ACTN3 R577X, and six polymorphisms in the PPARGC1A-NRF-TFAM pathway genes. The case athlete was heterozygous for the ACTN3 R577X variation and had five out of six 'endurance-oriented' genotypes, scoring significantly high in endurance 'optimal' genotype profile. In conclusion, we suggest that the case athlete is favoured by polygenic profile that is more suitable for mitochondrial biogenesis, regardless of his good phenotypic accomplishments in short-term running events.

PGC-1alpha downstream transcription factors NRF-1 and TFAM are genetic modifiers of Huntington disease

BACKGROUND

Huntington disease (HD) is an inherited neurodegenerative disease caused by an abnormal expansion of a CAG repeat in the huntingtin HTT (HD) gene. The primary genetic determinant of the age at onset (AO) is the length of the HTT CAG repeat; however, the remaining genetic contribution to the AO of HD has largely not been elucidated. Recent studies showed that impaired functioning of the peroxisome proliferator-activated receptor gamma coactivator 1a (PGC-1alpha) contributes to mitochondrial dysfunction and appears to play an important role in HD pathogenesis. Further genetic evidence for involvement of PGC-1alpha in HD pathogenesis was generated by the findings that sequence variations in the PPARGC1A gene encoding PGC-1alpha exert modifying effects on the AO in HD. In this study, we hypothesised that polymorphisms in PGC-1alpha downstream targets might also contribute to the variation in the AO.

RESULTS

In over 400 German HD patients, polymorphisms in the nuclear respiratory factor 1 gene, NRF-1, and the mitochondrial transcription factor A, encoded by TFAM showed nominally significant association with AO of HD. When combining these results with the previously described modifiers rs7665116 in PPARGC1A and C7028T in the cytochrome c oxidase subunit I (CO1, mt haplogroup H) in a multivariable model, a substantial proportion of the variation in AO can be explained by the joint effect of significant modifiers and their interactions, respectively.

CONCLUSIONS

These results underscore that impairment of mitochondrial function plays a critical role in the pathogenesis of HD and that upstream transcriptional activators of PGC-1alpha may be useful targets in the treatment of HD.

Gene variants related to the power performance of the Lithuanian athletes

ACE (I/D), ACTN3 (R/X), PPARGC1A (Gly482Ser) and PPARA (G/C) polymorphisms have been linked to the success in power-oriented sports through the intermediate phenotypes. The study involved 193 Lithuanian elite athletes and 250 controls. The measured phenotypic variables included short-term explosive muscle power (STEMP) and anaerobic alactic maximum power (AAMP). ACE DD genotype was more common among endurance athletes compared to the power athletes. The ACTN3 genotype frequencies of the elite athletes differed from those of non-elite athletes; however, there were no differences among the athletes and the control group across the PPARGC1A Gly482Ser genotypes. The frequency of PPARA CC genotype increased with the growing skill level of athletes (non-elite 2%, sub-elite 7.7%, elite 11.6%). The STEMP and AAMP were higher in the males than females and they were also higher in the power-oriented group compared to the endurance sports group. Success in power sports can be attributed to the ACE II, PPARGC1A SerSer, PPARA CC genotype in association with phenotypic characteristics such as AAMP and STEMP. ACTN3 XX genotype may not be critical but rather additive to endurance performance. The results show that high muscle power depends on both environmental and genetic factors.

Candidate genes for physical performance in the horse

Intense selection for speed, endurance or pulling power in the domestic horse (Equus caballus) has resulted in a number of adaptive changes in the phenotype required for elite athletic performance. To date, studies in humans have revealed a large number of genes involved in elite athletic performance, but studies in horses are rare. The horse genome assembly and bioinformation tools for genome analyses have been used to compare human performance genes with their equine orthologues, both to retrieve pathways for these genes and to investigate their chromosomal distribution. In this review, 28 candidate genes for equine performance are presented that have polymorphisms associated with human elite athletic performance and may have impact on athletic performance in horses. A significant accumulation of candidate genes was found on horse chromosomes 4 and 12. Genes involved in pathways for focal adhesion, regulation of actin cytoskeleton, neuroactive ligand-receptor interaction, and calcium signalling were over-represented. Genome-wide association studies for athletic performance in horses may benefit from the strong conserved synteny of the chromosomal arrangement of genes in humans and horses.

Variability in training-induced skeletal muscle adaptation

When human skeletal muscle is exposed to exercise training, the outcomes, in terms of physiological adaptation, are unpredictable. The significance of this fact has long been underappreciated, and only recently has progress been made in identifying some of the molecular bases for the heterogeneous response to exercise training. It is not only of great medical importance that some individuals do not substantially physiologically adapt to exercise training, but the study of the heterogeneity itself provides a powerful opportunity to dissect out the genetic and environmental factors that limit adaptation, directly in humans. In the following review I will discuss new developments linking genetic and transcript abundance variability to an individual's potential to improve their aerobic capacity or endurance performance or induce muscle hypertrophy. I will also comment on the idea that certain gene networks may be associated with muscle “adaptability” regardless the stimulus provided.

Association of single-nucleotide polymorphisms from 17 candidate genes with baseline symptom-limited exercise test duration and decrease in duration over 20 years: the Coronary Artery Risk Development in Young Adults (CARDIA) fitness study

BACKGROUND

It is not known whether the genes involved with endurance performance during young adulthood are also involved with changes in performance. We examined the associations of gene variants with symptom-limited exercise test duration at baseline and decrease in duration over 20 years.

METHODS AND RESULTS

A total of 3783 (1835 black, 1948 white) and 2335 (1035 black, 1300 white) participants from the Coronary Artery Risk Development in Young Adults study were included in the baseline and 20-year models, respectively. Two hundred seventeen single-nucleotide polymorphisms (SNPs) in black participants and 171 in white participants from 17 genes were genotyped. In blacks, 5 SNPs in the ATP1A2, HIF1A, NOS3, and PPARGC1A loci tended to be associated (P<0.05) with baseline duration in a multivariate regression model. Blacks (n=99) with at least 4 of the most-favorable genotypes at these loci had an ≈2-minute longer baseline duration than those with only 2 such genotypes (P<0.0001). In whites, the HIF1A rs1957757 and PPARGC1A rs3774909 markers tended to be associated with baseline duration, but the association of a multimarker construct of the most-favorable genotypes at both SNPs with baseline duration was not statistically significant. In whites, 4 SNPs in the AGT, AMPD1, ANG, and PPARGC1A loci tended to be associated with decrease in exercise duration over 20 years, and those with all 4 favorable genotypes (n=40) had a 0.8-minute less decline in duration compared with those with none or 1 (n=232) (P<0.0001).

CONCLUSIONS

In multimarker constructs, alleles at genes related to skeletal muscle Na(+)/K(+) transport, hypoxia, and mitochondrial metabolism are associated with symptom-limited exercise test duration over time in adults.

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.

Interaction between SNPs in the NRF2 gene and elite endurance performance

Nuclear respiratory factor 2 (NRF2), a member of the Cap-N-Collar family of transcription factors, plays an important role in the mitochondrial biogenesis, and variants of NRF2 gene have been associated with endurance performance. The aims of the present study were 1) to compare NRF2 A/C (rs12594956) and NRF2 C/T (rs8031031) genotype and allele frequencies between athletes of sports with different demands (endurance vs. sprinters) as well as between competitive levels (elite level vs. national level) and 2) to analyze the interaction of these two polymorphisms and its influence on the level of endurance performance. One hundred and fifty-five track and field athletes (74 endurance athletes and 81 sprinters) and 240 nonathletic healthy individuals participated in this study. Endurance athletes presented a higher frequency of the AA (rs12594956) and CT (rs8031031) genotypes than sprinters and the control group, as well as higher A and T alleles, respectively. These differences did not appear between the sprinters and control subjects. The odds ratio for harboring the “optimal genotype” ( NRF2 AA+ NRF2 CT) was 4.53 (95% confidence interval 1.23–16.6) in the whole cohort of endurance athletes and 6.55 (95% confidence interval 1.12–38.25) in elite-level endurance athletes, compared with control subjects and both levels of sprinters. In conclusion, our data indicate that the NRF2 A/C and NRF2 C/T single nucleotide polymorphisms (SNPs) are associated, separately and in combination, with elite endurance athletes, which supports the notion that these specific gene variants might belong to a growing group of SNPs that are associated with endurance performance.

Associations of polymorphisms of eight muscle- or metabolism-related genes with performance in Mount Olympus marathon runners

Athletic endurance performance is probably partly under genetic control, but genetic association studies have yielded inconclusive results. The objective of the present study was to evaluate the association of polymorphisms in eight muscle- or metabolism-related genes with endurance performance in participants of the Olympus Marathon running race. We recruited 438 athletes who participated in the 2007 and 2008 annual running events of the Olympus Marathon: a 43.8-km race with an ascent from sea level to 2,690-m altitude and then a descent to 300 m. Phenotypes of interest were the competitive event time at the specific Olympus Marathon where the athlete was enrolled, the fastest reported timing ever achieved in an Olympus Marathon, and how many kilometers per week the athlete ran during the previous year. Eleven polymorphisms in alpha(3)-actinin (ACTN3), AMP deaminase-1 (AMPD1), bradykinin B(2) receptor (BDKRB2), beta(2)-adrenergic receptor (ADRB2), peroxisome proliferator-activated receptor (PPAR)-gamma coactivator-1 alpha (PPARGC1A), PPAR-alpha (PPARA), PPAR-delta (PPARD), and apoliprotein E (APOE) were evaluated. Hardy-Weinberg equilibrium testing on the overall cohort of male athletes showed a significant deviation for BDKRB2 rs1799722 (P = 0.018; P = 0.006 when limited to 316 habitual male runners) with an excess of the TT genotype. Across all athletes, no associations showed nominal statistical significance for any of the three phenotypes, and the same was true when analyses were limited to men (n = 417). When limited to 316 male athletes who identified running as their preferred sport, ADRB2 rs1042713 had nominally significant associations with faster times for the minor (A) allele for the fastest time ever (P = 0.01). The direction of effect was identical as previously postulated only for BDKRB2 rs1799722 and ADRB2 rs1042713, indicating consistency. BDKRB2 rs1799722 and ADRB2 rs1042713 have some support for being implicated in endurance performance among habitual runners and require further investigation.

Genetics of athletic performance

Performance enhancing polymorphisms (PEPs) are examples of natural genetic variation that affect the outcome of athletic challenges. Elite athletes, and what separates them from the average competitor, have been the subjects of discussion and debate for decades. While training, diet, and mental fitness are all clearly important contributors to achieving athletic success, the fact that individuals reaching the pinnacle of their chosen sports often share both physical and physiological attributes suggests a role for genetics. That multiple members of a family often participate in highly competitive events, such as the Olympics, further supports this argument. In this review, we discuss what is known regarding the genes and gene families, including the mitochondrial genome, that are believed to play a role in human athletic performance. Where possible, we describe the physiological impact of the critical gene variants and consider predictions about other potentially important genes. Finally, we discuss the implications of these findings on the future for competitive athletics.

Is there an interaction between PPARD T294C and PPARGC1A Gly482Ser polymorphisms and human endurance performance?

Functional Gly482Ser (rs8192678) and T294C (rs2016520) polymorphisms in the peroxisome proliferator-activated receptor gamma coactivator-1 (PPARGC1A) and peroxisome proliferator-activated receptor delta (PPARD) genes, respectively, have been associated with mRNA and/or protein activity. The aim of this study was to determine their frequency distribution among 155 Israeli athletes (endurance athletes and sprinters) and 240 healthy control subjects. There were no differences between the endurance athletes, the sprinters and the control group across the PPARD T294C genotypes (P = 0.62). Similarly, no statistical differences were found between the subgroups of elite-level endurance athletes (those who had represented Israel in a world track and field championship or in the Olympic Games) and national-level endurance athletes (P = 0.3), or between elite-level and national-level sprinters (P = 0.9). However, a combined influence of these two polymorphisms on endurance performance was found. The PPARD CC + PPARGC1A Gly/Gly genotypes were more frequently found in the elite endurance athletes than in national-level endurance athletes (P < 0.000). In the cohort of endurance athletes, the odds ratio of the 'optimal genotype' for endurance athletes (PPARD CC + PPARGC1A Gly/Gly + PPARGC1A Gly/Ser) being an elite-level athlete was 8.32 (95% confidence interval 2.2-31.4). In conclusion, the present study suggests that PPARD T294C is not associated with endurance performance. However, a higher frequency of the PPARGC1A Gly/Gly + PPARD CC genotype is associated with elite-level endurance athletes.

Short-term exercise training does not stimulate skeletal muscle ATP synthesis in relatives of humans with type 2 diabetes

OBJECTIVE

We tested the hypothesis that short-term exercise training improves hereditary insulin resistance by stimulating ATP synthesis and investigated associations with gene polymorphisms.

RESEARCH DESIGN AND METHODS

We studied 24 nonobese first-degree relatives of type 2 diabetic patients and 12 control subjects at rest and 48 h after three bouts of exercise. In addition to measurements of oxygen uptake and insulin sensitivity (oral glucose tolerance test), ectopic lipids and mitochondrial ATP synthesis were assessed using(1)H and(31)P magnetic resonance spectroscopy, respectively. They were genotyped for polymorphisms in genes regulating mitochondrial function, PPARGC1A (rs8192678) and NDUFB6 (rs540467).

RESULTS

Relatives had slightly lower (P = 0.012) insulin sensitivity than control subjects. In control subjects, ATP synthase flux rose by 18% (P = 0.0001), being 23% higher (P = 0.002) than that in relatives after exercise training. Relatives responding to exercise training with increased ATP synthesis (+19%, P = 0.009) showed improved insulin sensitivity (P = 0.009) compared with those whose insulin sensitivity did not improve. A polymorphism in the NDUFB6 gene from respiratory chain complex I related to ATP synthesis (P = 0.02) and insulin sensitivity response to exercise training (P = 0.05). ATP synthase flux correlated with O(2)uptake and insulin sensitivity.

CONCLUSIONS

The ability of short-term exercise to stimulate ATP production distinguished individuals with improved insulin sensitivity from those whose insulin sensitivity did not improve. In addition, the NDUFB6 gene polymorphism appeared to modulate this adaptation. This finding suggests that genes involved in mitochondrial function contribute to the response of ATP synthesis to exercise training.

NRF2 intron 3 A/G polymorphism is associated with endurance athletes' status

The aim of this study was to determine the frequency distribution of nuclear respiratory factor 2 (NRF2) intron 3 A/G polymorphism (rs7181866) among 155 Israeli athletes (endurance athletes and sprinters) and 240 healthy controls. Results showed that there was a significantly higher proportion of the AG genotype, rather than the AA genotype, in the group of endurance athletes compared with the sprinters (P = 0.014) and controls (P = 0.0008). However, the sprinters' genotype and allele frequencies were similar to those of the control group (P = 0.62 for genotype distribution percentage). These results were even more pronounced when we compared between the subgroups of 20 elite endurance athletes (those who had represented Israel in a world track-and-field championship or in the Olympic Games) and 54 national-level endurance athletes. In the group of elite endurance athletes the G allele was more frequent than in the national-level endurance athletes (P = 0.047). We conclude that 1) in Israeli athletes the NRF2 AG genotype is more frequent in elite endurance athletes than in sprinters, and 2) within the endurance group the NRF2 AG genotype and the G allele are more frequent in elite athletes, suggesting a positive association between the AG genotype, and possibly the G allele, and the likelihood of being an elite endurance athlete.

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.

PPARGC1A sequence variation and cardiovascular risk-factor levels: a study of the main genetic effects and gene x environment interactions in children from the European Youth Heart Study

AIMS/HYPOTHESIS

The PPARGC1A gene coactivates multiple nuclear transcription factors involved in cellular energy metabolism and vascular stasis. In the present study, we genotyped 35 tagging polymorphisms to capture all common PPARGC1A nucleotide sequence variations and tested for association with metabolic and cardiovascular traits in 2,101 Danish and Estonian boys and girls from the European Youth Heart Study, a multicentre school-based cross-sectional cohort study.

METHODS

Fasting plasma glucose concentrations, anthropometric variables and blood pressure were measured. Habitual physical activity and aerobic fitness were objectively assessed using uniaxial accelerometry and a maximal aerobic exercise stress test on a bicycle ergometer, respectively.

RESULTS

In adjusted models, nominally significant associations were observed for BMI (rs10018239, p = 0.039), waist circumference (rs7656250, p = 0.012; rs8192678 [Gly482Ser], p = 0.015; rs3755863, p = 0.02; rs10018239, beta = -0.01 cm per minor allele copy, p = 0.043), systolic blood pressure (rs2970869, p = 0.018) and fasting glucose concentrations (rs11724368, p = 0.045). Stronger associations were observed for aerobic fitness (rs7656250, p = 0.005; rs13117172, p = 0.008) and fasting glucose concentrations (rs7657071, p = 0.002). None remained significant after correcting for the number of statistical comparisons. We proceeded by testing for gene x physical activity interactions for the polymorphisms that showed nominal evidence of association in the main effect models. None of these tests was statistically significant.

CONCLUSIONS/INTERPRETATION

Variants at PPARGC1A may influence several metabolic traits in this European paediatric cohort. However, variation at PPARGC1A is unlikely to have a major impact on cardiovascular or metabolic health in these children.

Is there an optimum endurance polygenic profile?

We analysed seven genetic polymorphisms that are candidates to explain individual variations in human endurance phenotypic traits, at least in Caucasian people (ACE Ins/Del, ACTN3 Arg577Ter, AMPD1 Gln12Ter, CKMM 1170 bp/985 + 185 bp, HFE His63Asp, GDF-8 Lys153Arg and PPARGC1A Gly482Ser) in 46 world-class endurance athletes and 123 controls (all Spanish Caucasians). Using the model developed by Williams & Folland we determined (1) the 'total genotype score' (TGS, from the accumulated combination of the seven polymorphisms, with a maximum value of '100' for the theoretically optimal polygenic score) in the non-athlete (control) group, in the athlete group and in the total Spanish population, and (2) the probability for the occurrence of Spanish individuals with the 'perfect' polygenic endurance profile (i.e. TGS = 100). The probability of a Spanish individual possessing a theoretically optimal polygenic profile for up to the seven candidate genetic polymorphisms we studied was very small, i.e. approximately 0.07% (or 1 in 1351 Spanish individuals). The mean TGS was higher in athletes (70.22 +/- 15.58) than in controls (62.43 +/- 11.45) and also higher than predicted for the total Spanish population (60.80 +/- 12.1), suggesting an overall more 'favourable' polygenic profile in the athlete group. However, only three of the best Spanish endurance athletes (who are also amongst the best in the world) had the best possible score for up to six genes and none of them had the optimal profile. Other polymorphisms yet undiscovered as well as several factors independent of genetic endowment may explain why some individuals reach the upper end of the endurance performance continuum.

Exercise and the treatment of diabetes and obesity

Lifestyle intervention programs encompassing exercise and healthy diets are an option for the treatment and management of obesity and type 2 diabetes and have long been known to exert beneficial effects on whole-body metabolism, in particular leading to enhanced insulin-sensitivity. Obesity is associated with increased risk of several illnesses and premature mortality. However, physical inactivity is itself associated with a number of similar risks, independent of body-mass index, and is an independent risk factor for more than 25 chronic diseases, including type 2 diabetes and cardiovascular disease. This article addresses the debate regarding the relative effects of physical exercise itself and the effect of exercise-induced weight loss.

The Gly482Ser genotype at the PPARGC1A gene and elevated blood pressure: a meta-analysis involving 13,949 individuals

The protein encoded by the PPARGC1A gene is expressed at high levels in metabolically active tissues and is involved in the control of oxidative stress via reactive oxygen species detoxification. Several recent reports suggest that the PPARGC1A Gly482Ser (rs8192678) missense polymorphism may relate inversely with blood pressure. We used conventional meta-analysis methods to assess the association between Gly482Ser and systolic (SBP) or diastolic blood pressures (DBP) or hypertension in 13,949 individuals from 17 studies, of which 6,042 were previously unpublished observations. The studies comprised cohorts of white European, Asian, and American Indian adults, and adolescents from South America. Stratified analyses were conducted to control for population stratification. Pooled genotype frequencies were 0.47 (Gly482Gly), 0.42 (Gly482Ser), and 0.11 (Ser482Ser). We found no evidence of association between Gly482Ser and SBP [Gly482Gly: mean = 131.0 mmHg, 95% confidence interval (CI) = 130.5-131.5 mmHg; Gly482Ser mean = 133.1 mmHg, 95% CI = 132.6-133.6 mmHg; Ser482Ser: mean = 133.5 mmHg, 95% CI = 132.5-134.5 mmHg; P = 0.409] or DBP (Gly482Gly: mean = 80.3 mmHg, 95% CI = 80.0-80.6 mmHg; Gly482Ser mean = 81.5 mmHg, 95% CI = 81.2-81.8 mmHg; Ser482Ser: mean = 82.1 mmHg, 95% CI = 81.5-82.7 mmHg; P = 0.651). Contrary to previous reports, we did not observe significant effect modification by sex (SBP, P = 0.966; DBP, P = 0.715). We were also unable to confirm the previously reported association between the Ser482 allele and hypertension [odds ratio: 0.97, 95% CI = 0.87-1.08, P = 0.585]. These results were materially unchanged when analyses were focused on whites only. However, statistical evidence of gene-age interaction was apparent for DBP [Gly482Gly: 73.5 (72.8, 74.2), Gly482Ser: 77.0 (76.2, 77.8), Ser482Ser: 79.1 (77.4, 80.9), P = 4.20 x 10(-12)] and SBP [Gly482Gly: 121.4 (120.4, 122.5), Gly482Ser: 125.9 (124.6, 127.1), Ser482Ser: 129.2 (126.5, 131.9), P = 7.20 x 10(-12)] in individuals <50 yr (n = 2,511); these genetic effects were absent in those older than 50 yr (n = 5,088) (SBP, P = 0.41; DBP, P = 0.51). Our findings suggest that the PPARGC1A Ser482 allele may be associated with higher blood pressure, but this is only apparent in younger adults.

Similarity of polygenic profiles limits the potential for elite human physical performance

Human physical capability is influenced by many environmental and genetic factors, and it is generally accepted that physical capability phenotypes are highly polygenic. However, the ways in which relevant polymorphisms combine to influence the physical capability of individuals and populations are unknown. Initially, the literature was searched to identify associations between 23 genetic polymorphisms and human endurance phenotypes. Next, typical genotype frequencies of those polymorphisms in the general population were obtained from suitable literature. Using probability calculations, we found only a 0.0005% chance of a single individual in the world having the 'preferable' form of all 23 polymorphisms. As the number of DNA variants shown to be associated with human endurance phenotypes continues to increase, the probability of any single individual possessing the 'preferable' form of each polymorphism will become even lower. However, with population turnover, the chance of such genetically gifted individuals existing increases. To examine the polygenic endurance potential of a human population, a 'total genotype score' (for the 23 polymorphisms) was calculated for each individual within a hypothetical population of 1000 000. There was considerable homogeneity in terms of genetic predisposition to high endurance potential, with 99% of people differing by no more than seven genotypes from the typical profile. Consequently, with population turnover world and Olympic records should improve even without further enhancement of environmental factors, as more 'advantageous' polygenic profiles occasionally, though rarely, emerge. More broadly, human potential appears limited by the similarity of polygenic profiles at both the 'elite sport' and 'chronic disorder' ends of the performance continuum.

Genotype modulators of clinical severity in McArdle disease

The phenotypic manifestation of McArdle disease varies considerably from one individual to the next. The purpose of this study was to assess the possible association between the clinical severity of the disease, and each of the genotypes PYGM (R50X), ACE (I/D), AMPD1 (Q12X), PPARGC1A (G482S) and ACTN3 (R577X). We also assessed links between clinical disease severity and other potential phenotype modulators such as age or gender. McArdle disease was diagnosed in 99 patients of Spanish origin (60 male, 39 female; age range 8-81 years) by identifying the two mutant alleles of the PYGM gene. Disease severity was assessed using the grading scheme previously reported by Martinuzzi et al. [A. Martinuzzi, E. Sartori, M. Fanin, et al., Phenotype modulators in myophosphorylase deficiency, Ann. Neurol. 53 (2003) 497-502]. Significant correlation was observed (exact two-sided P<0.0001) between the number of D alleles of the ACE gene and the disease severity score. Rank-order correlation coefficients were 0.296 (95% CI: 0.169, 0.423) (Kendall's tau) and 0.345 (95% CI: 0.204, 0.486) (Somer's D). No significant relationships were detected between clinical severity and the remaining genotypes examined. Finally, disease severity was significantly worse in women with the disease. Our findings indicate that both ACE genotype and gender contribute to how McArdle disease manifests in an individual patient. The role of other candidate genes remains to be elucidated.

Is there an association between PPARGC1A genotypes and endurance capacity in Chinese men?

Our purpose was to determine the possible association between genotypes of three polymorphisms (Gly482Ser, Thr394Thr and A2962G) of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) gene, on one hand, and both the pre- (baseline) and post-training levels of maximal (i.e., maximal oxygen uptake [VO2max]) and submaximal human endurance capacity (i.e., running economy [RE]). We studied 102 young males (physically active, non-athletes; age: 19+/-1 yrs) from Northern China (of Han origin) who underwent a 18-week endurance training (running) program and were tested on a treadmill (for VO2max and RE determination) before and after training. None of the VO2max and RE related traits were associated with the Gly482Ser and Thr394Thr polymorphisms at baseline or after training. The A2962G polymorphism was however associated with VO2max at baseline, as carriers of the G allele (AG+GG genotypes; n=49) had higher levels of VO2max than the AA group (n=53) (58.2+/-4.3 vs 56.3+/-3.9 mL/kg/min; P=0.017). Our results do not support previous data on Caucasians showing an association between the Gly482Ser variant and VO2max but suggest the potential role of another polymorphism (A2962G) to explain individual VO2max differences in Chinese men.

Genetic variations in PPARD and PPARGC1A determine mitochondrial function and change in aerobic physical fitness and insulin sensitivity during lifestyle intervention

CONTEXT

Mitochondrial function is associated with aerobic physical fitness and insulin sensitivity and may play an important role in the pathophysiology of type 2 diabetes. Peroxisome proliferator-activated receptor (PPAR)-delta (gene PPARD) and PPARgamma coactivator 1alpha (gene PPARGC1A) are determinants of mitochondrial function in animals and in vitro.

OBJECTIVE

The objective of this study was to establish whether single-nucleotide polymorphisms (SNPs) in PPARD and PPARGC1A modulate the effect of exercise training on change in aerobic physical fitness and insulin sensitivity and whether they affect mitochondrial function in human myotubes in vitro.

SETTING

The study setting was the Tuebingen Lifestyle Intervention Program in a university teaching hospital.

RESULTS

After 9 months of intervention, the minor G allele of SNP rs2267668 in PPARD and the minor serine-encoding allele of the common Gly482Ser SNP in PPARGC1A were independently associated with less increase in individual anaerobic threshold (n = 136, P = 0.002 and P = 0.005), a precise measurement of aerobic physical fitness. Moreover, individual anaerobic threshold (+11%) and insulin sensitivity (+4%) increased less in subjects carrying the minor alleles at both SNPs (X/G-X/Ser), compared with homozygous carriers of the major alleles (A/A-Gly/Gly, +120% and +40%; P < 0.0001 and P = 0.015), suggesting an additive effect of the SNPs. In addition, low skeletal muscle mitochondrial function in vitro was detected in young carriers of the G allele of the SNP rs2267668 in PPARD (n = 19, P = 0.02).

CONCLUSIONS

These data provide evidence that the rs2267668 A/G SNP in PPARD and the Gly482Ser SNP in PPARGC1A have both independent and additive effects on the effectiveness of aerobic exercise training to increase aerobic physical fitness and insulin sensitivity.

The human gene map for performance and health-related fitness phenotypes: the 2005 update

The current review presents the 2005 update of the human gene map for physical performance and health-related fitness phenotypes. It is based on peer-reviewed papers published by the end of 2005. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed, but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, in the early version of the gene map, 29 loci were depicted. In contrast, the 2005 human gene map for physical performance and health-related phenotypes includes 165 autosomal gene entries and QTL, plus five others on the X chromosome. Moreover, there are 17 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes. Thus, the map is growing in complexity. Unfortunately, progress is slow in the field of genetics of fitness and performance, primarily because the number of laboratories and scientists focused on the role of genes and sequence variations in exercise-related traits continues to be quite limited.

PGC-1alpha gene and physical activity in type 2 diabetes mellitus

Exercise stimulates PGC-1alpha gene expression and increases V O2max, the latter of which relates inversely with type 2 diabetes risk. Consistently, low levels of PGC-1alpha mRNA and nucleotide sequence variation at PGC-1alpha associate with lower level of V O2max and increased diabetes risk. Thus, PGC-1alpha sequence variation may interact with physical activity to modify diabetes risk via changes in oxidative energy metabolism.

Human skeletal muscle fibre type variations correlate with PPAR alpha, PPAR delta and PGC-1 alpha mRNA

AIMS

Studies from genetically modified animals have been instrumental in highlighting genes and their products involved in the regulation of muscle fibre type and oxidative phenotypes; however, evidence in humans is limited. Our aim was therefore to investigate expression of those genes implicated in the regulation of oxidative fibre phenotypes in humans.

METHODS

Using quantitative polymerase chain reaction we determined mRNA expression of selected genes in skeletal muscle from three different groups, displaying physiological and pathological variations in muscle fibre type, activity and skeletal muscle metabolism respectively: (i) elite athletes (cyclists), with an increased proportion of type I slow twitch, oxidative fibres, (ii) normally active subjects with an average fibre type distribution, and (iii) spinal cord-injured subjects with a low proportion of type I fibres.

RESULTS

Skeletal muscle mRNA expression of calcineurin Aalpha and Abeta, peroxisome proliferator-activated receptor (PPAR)-alpha and -delta, and PPAR gamma coactivator (PGC)-1alpha and -1beta was determined. Calcineurin Aalpha and calcineurin Abeta mRNA expression was similar between groups. In contrast, mRNA expression of PPARalpha, PPARdelta, PGC-1alpha and -1beta was increased in athletes, when compared with normally active subjects. Furthermore, mRNA expression of PPARalpha, PPARdelta, PGC-1alpha and -1beta was reduced in spinal cord-injured subjects. Additionally, PPARalpha, PPARdelta and PGC-1alpha correlated with oxidative fibre content.

CONCLUSION

Skeletal muscle mRNA expression of PPARalpha, PPARdelta, PGC-1alpha and -1beta reflects differences in type I muscle fibres associated with pathologically and physiologically induced skeletal muscle fibre type differences.

Alterations of blood pressure in type 1 diabetic children and adolescents

The aim of this study was to assess the association between metabolic control, microalbuminuria, and diabetic nephropathy with ambulatory blood pressure monitoring (ABPM) in normotensive individuals with type 1 diabetes mellitus (DM). ABPM was undertaken in 68 normotensive type 1 diabetic patients with a mean age of 14.4+/-4.2 years. Microalbuminuria was diagnosed on the basis of a urinary albumin excretion rate grater than 20 microg/min in two of the three 24-h urine collections. Hypertension (HT) frequency was greater in the microalbuminuric patients than normoalbuminuric patients (54 vs 17.54%, p=0.05) with ABPM. Microalbuminuric patients had a higher diastolic pressure burden than normoalbuminuric patients. There were no differences in systolic and diastolic dips between the two groups. Diastolic pressure loads in all periods showed a significant correlation with duration of diabetes, mean HbA1c from the onset of diabetes, and level of microalbuminuria. Nocturnal dipping was reduced in 41.2% of the patients. In the normoalbuminuric group 41.1% and in the microalbuminuric group 63.6% were nondippers. Our data demonstrate higher 24-h and daytime diastolic blood pressure load and loss of nocturnal dip in type 1 diabetic adolescents and children. High diastolic blood pressure burden in diabetic patients could represent a risk for nephropathy.

Meta-analysis of the Gly482Ser variant in PPARGC1A in type 2 diabetes and related phenotypes

AIMS/HYPOTHESIS

Peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PPARGC1A) is a transcriptional co-activator with a central role in energy expenditure and glucose metabolism. Several studies have suggested that the common PPARGC1A polymorphism Gly482Ser may be associated with risk of type 2 diabetes, with conflicting results. To clarify the role of Gly482Ser in type 2 diabetes and related human metabolic phenotypes we genotyped this polymorphism in a case-control study and performed a meta-analysis of relevant published data.

MATERIALS AND METHODS

Gly482Ser was genotyped in a type 2 diabetes case-control study (N=1,096) using MassArray technology. A literature search revealed publications that examined Gly482Ser for association with type 2 diabetes and related metabolic phenotypes. Meta-analysis of the current study and relevant published data was undertaken.

RESULTS

In the pooled meta-analysis, including data from this study and seven published reports (3,718 cases, 4,818 controls), there was evidence of between-study heterogeneity (p<0.1). In the fixed-effects meta-analysis, the pooled odds ratio for risk of type 2 diabetes per Ser482 allele was 1.07 (95% CI 1.00-1.15, p=0.044). Elimination of one of the studies from the meta-analysis gave a summary odds ratio of 1.11 (95% CI 1.04-1.20, p=0.004), with no between-study heterogeneity (p=0.475). For quantitative metabolic traits in normoglycaemic subjects, we also found significant between-study heterogeneity. However, no significant association was observed between Gly482Ser and BMI, fasting glucose or fasting insulin.

CONCLUSIONS/INTERPRETATION

This meta-analysis of data from the current and published studies supports a modest role for the Gly482Ser PPARGC1A variant in type 2 diabetes risk.