Genetic characterization of physical activity behaviours in university students enrolled in kinesiology degree programs

The ACTN3 R577X polymorphism is associated with metabolic alterations in a sex-dependent manner in subjects from western Mexico

BACKGROUND

The ACTN3 gene is primarily expressed in fast skeletal muscle fibres. A common nonsense polymorphism in this gene is ACTN3 R577X (rs1815739), which causes an absolute deficiency of α-actinin-3 protein and alterations in muscle metabolism. Considering metabolic alterations are influenced by nutrition and genetic factors, as well as lifestyle factors, we hypothesise a possible association of the ACTN3 R577X polymorphism with metabolic alterations.

METHODS

In this cross-sectional study, 397 adults met the inclusion criteria. Body composition was measured by electrical bioimpedance. Dietary data were analysed using Nutritionist Pro™ software. Biochemical variables were determined by dry chemistry. Genomic DNA was extracted from peripheral leukocytes and genotyping of the ACTN3 R577X polymorphism was determined by allelic discrimination using TaqMan probes. The statistical analyses were performed using SPSS statistical software. p < 0.05 was considered statistically significant.

RESULTS

The ACTN3 577XX genotype was associated with high glucose, triglyceride and very low density lipoprotein-cholesterol levels and a higher frequency of hypertriglyceridaemia and insulin resistance in women. In males, the genetic variant showed a trend towards significance for insulin resistance.

CONCLUSIONS

The ACTN3 R577X polymorphism was associated with metabolic alterations in women and a tendency was observed in men variant carriers. Thus, this common genetic variant could be implicated in the development of chronic metabolic diseases.

Genetic variants related to physical activity or sedentary behaviour: a systematic review

BACKGROUND

Research shows that part of the variation in physical activity and sedentary behaviour may be explained by genetic factors. Identifying genetic variants associated with physical activity and sedentary behaviour can improve causal inference in physical activity research. The aim of this systematic review was to provide an updated overview of the evidence of genetic variants associated with physical activity or sedentary behaviour.

METHODS

We performed systematic literature searches in PubMed and Embase for studies published from 1990 to April 2020 using keywords relating to "physical activity", "exercise", "sedentariness" and "genetics". Physical activity phenotypes were either based on self-report (e.g., questionnaires, diaries) or objective measures (e.g., accelerometry, pedometer). We considered original studies aiming to i) identify new genetic variants associated with physical activity or sedentary behaviour (i.e., genome wide association studies [GWAS]), or ii) assess the association between known genetic variants and physical activity or sedentary behaviour (i.e., candidate gene studies). Study selection, data extraction, and critical appraisal were carried out by independent researchers, and risk of bias and methodological quality was assessed for all included studies.

RESULTS

Fifty-four out of 5420 identified records met the inclusion criteria. Six of the included studies were GWAS, whereas 48 used a candidate gene approach. Only one GWAS and three candidate gene studies were considered high-quality. The six GWAS discovered up to 10 single nucleotide polymorphisms (SNPs) associated with physical activity or sedentariness that reached genome-wide significance. In total, the candidate gene studies reported 30 different genes that were associated (p < 0.05) with physical activity or sedentary behaviour. SNPs in or close to nine candidate genes were associated with physical activity or sedentary behaviour in more than one study.

CONCLUSION

GWAS have reported up to 10 loci associated with physical activity or sedentary behaviour. Candidate gene studies have pointed to some interesting genetic variants, but few have been replicated. Our review highlights the need for high-quality GWAS in large population-based samples, and with objectively assessed phenotypes, in order to establish robust genetic instruments for physical activity and sedentary behaviour. Furthermore, consistent replications in GWAS are needed to improve credibility of genetic variants.

TRIAL REGISTRATION

Prospero CRD42019119456 .