Genetic association research in football: A systematic review.

Genetic variation is responsible for a large amount of the inter-individual performance disparities seen in sport. As such, in the last ten years genetic association studies have become more common; with one of the most frequently researched sports being football. However, the progress and methodological rigour of genetic association research in football is yet to be evaluated. Therefore, the aim of this paper was to identify and evaluate all genetic association studies involving football players and outline where and how future research should be directed. Firstly, a systematic search was conducted in the Pubmed and SPORTDiscus databases, which identified 80 eligible studies. Progression analysis revealed that 103 distinct genes have been investigated across multiple disciplines; however, research has predominately focused on the association of the ACTN3 or ACE gene. Furthermore, 55% of the total studies have been published within the last four years; showcasing that genetic association research in football is increasing at a substantial rate. However, there are several methodological inconsistencies which hinder research implications, such as; inadequate description or omission of ethnicity and on-field positions. Furthermore, there is a limited amount of research on several key areas crucial to footballing performance, in particular; psychological related traits. Moving forward, improved research designs, larger sample sizes, and the utilisation of genome-wide and polygenic profiling approaches are recommended. Finally, we introduce the Football Gene Project, which aims to address several of these limitations and ultimately facilitate greater individualised athlete development within football.Highlights Genetic association research in football (soccer) is increasing at a substantial rate but has predominately focused on the ACTN3 R577X and ACE I/D polymorphisms.Inconsistent reporting of ethnicity and on-field positions, along with the prevalence of analysing athletes of multiple sports together in small samples, hinders research implications.Additional research on psychological related traits and the increased utilisation of genome-wide and polygenic profiling approaches are required.The authors introduce the Football Gene Project, which seeks to address several of the current limitations through the collaboration of multiple professional football organisations.