Maturity-Associated Polygenic Profiles of under 12-16-Compared to under 17-23-Year-Old Male English Academy Football Players.

The purpose of this study was to examine polygenic profiles previously associated with maturity timing in male academy football players across different age phases. Thus, 159 male football players from four English academies (U12-16, = 86, aged 13.58 ± 1.58 years; U17-23, = 73, aged 18.07 ± 1.69 years) and 240 male European controls were examined. Polygenic profiles comprised 39 single nucleotide polymorphisms and were analysed using unweighted and weighted total genotype scores (TGSs; TWGSs). There were significant differences in polygenic profiles between groups, whereby U17-23 players had more genetic variants associated with later maturity compared to U12-16 players (TGS, = 0.010; TWGS, = 0.024) and controls (TGS, = 0.038; TWGS, = 0.020). More specifically, U17-23 players had over two-times the odds of possessing >36 later-maturing alleles than <30 compared to U12-16 players (odds ratio (OR) = 2.84) and controls (OR = 2.08). These results suggest there was a greater proportion of relatively later-maturing players as maturation plateaus towards adulthood, which may be explained by the 'underdog hypothesis'. This study provides the first known molecular evidence that supports the notion that a maturity selection bias exists within male academy football.