Evaluating a Genome-Wide Polygenic Score for Handgrip Strength and Its Interplay with Leisure-Time Physical Activity Across the IGEMS Twin Cohorts.

PURPOSE: Polygenic scores (PGSs) may help assess genetic predisposition to multifactorial traits. We examined whether age, sex, and leisure-time physical activity (LTPA) modify the association between a PGS for handgrip strength (HGS) and measured HGS in older adults.

METHODS

PGS for HGS (PGS hgs) , based on Pan-UK Biobank genome-wide association study data, was calculated for 5103 participants (aged 40-96; 44% women) from eight twin cohorts in Denmark, Sweden, Australia, the United States, and Finland within the IGEMS consortium. Sex-standardized HGS and self-reported LTPA were assessed cross-sectionally. Linear mixed models estimated associations between PGS hgs and HGS, including interactions with age, country, and LTPA, as well as an association between PGS hgs and LTPA. Fixed-effect within-pair models were conducted to assess environmental contributions.

RESULTS

Higher PGS hgs was associated with greater HGS (β = 2.14, SE = 0.15, P < 0.001), explaining 4.6% of HGS variance overall, with modest variation across countries. In sex-stratified models, PGS hgs explained 5.2% of the variance in females and 4.3% in males. No statistically significant interaction with age was found. A significant PGS hgs × LTPA interaction (β = -0.034, P = 0.013) indicated that the association between LTPA and HGS was more pronounced among individuals with lower PGS hgs . The within-pair models offered limited support for the independent environmental impact of LTPA.

CONCLUSIONS

The PGS hgs was associated with measured HGS in the meta-analysis, highlighting the potential of PGSs to capture individual differences in strength-related traits across populations. The association of PGS hgs with HGS was moderated by LTPA, such that the beneficial impact of LTPA on HGS was greater among individuals with a lower genetic propensity for HGS.