The anxiety level of an athlete is important. The serotonin transporter protein is encoded by the SLC6A4 gene. Serotonin is one of the most important members of anxiety metabolism. Serotonin transporter protein plays a role in bringing serotonin back from the synaptic space to the presynaptic neuron. We aimed to determine the genotype and allele distributions of the SLC6A4 promoter L/S polymorphism in football players and compare it with the control group. For this purpose, 20 football players participated in our study. Genotyping was performed by PCR after DNAs were isolated from buccal epithelial cells. When we examined the genotype distributions, the LL, LS and SS were found as 4 (20%), 8 (40%) and 8 (40%), respectively. In the control group, the same genotype number and percentages were determined as 10 (23%), 25 (57%) and 9 (20%), respectively. In terms of genotype distribution, no statistically significant significance was found between the two groups (p = 0.2493). When allelic distributions were examined in the athlete group, the L allele was counted as 16 (40%) and the S allele as 24 (60%). In the control group, the L allele 45 (51%) and the S allele were counted as 43 (49%). When the two groups were compared statistically in terms of allelic distribution, no statistically significant difference was found (p = 0.2423). As a result, LS and SS genotype were co-dominant and at the same time higher than LL genotype. At the same time, when we compared the S allele with the L allele, it was found that the S allele was more in percentage. Studies have found that the S allele is associated with anxiety. Sports psychologist can support athletes with S allele who are prone to anxiety problems. This is the first study to report that S allele is more common than L allele in Turkish football players.

With the human genome project, in addition to determining the number, structure and physical maps of our genes which were previously supposed to be between 20-25 thousands, genetic regions affecting athletic performance have also been identified.It has been determined that endurance, athletic ability and musculoskeletal as well as central nervous system (CNS) are effective in succeeding in today’s sporting events and play an important role in performance. Parameters affecting psychological performance such as stress, anxiety, aggression are effective in determining sportive achievements. Determining the genetic predisposition of the athletes in stressful environments or in sports where stress is prominent allows them to be guided by psychologists at an early age and contributes to sporting success. Related to the behavioral characteristics of the athletes, genes leading to resistance to stress, personality traits and aggressive behaviours like 5-HTT, DRD4, DRD5, ADRD1, COMT, BDNF, NRG1, GLUT4 and SLC2A4 and polymorphisms within these genes have been investigated in our review.