An increase in copy number of Myosin Light Chain Kinase 1 associates with increased force production in Lithuanian athletes

Abstract

Copy number variation has been linked to the development of various diseases, however copy number variants have not been investigated for associations with athletic performance. The present study investigated copy number variation of the Myosin Light Chain Kinase (MYLK)1 and MYLK-Antisense 1 (MYLK-AS1) genes for associations with athletic performance in a cohort of Lithuanian athletes and controls. We hypothesised that increased MYLK1 copy number and decreased MYLK-AS1 copy number would be associated with strength and power athletes (STP) and measures of muscle performance. DNA was extracted from blood samples of 407 athletes and controls. Copy number of the target genes was determined using a multiplexed quantitative-polymerase chain reaction and the use of a multicopy reference assay. A higher MYLK1 copy number was overrepresented in the STP compared with controls (p=0.028[OR=9.97, 95% CI: 1.19-83.81); however endurance athletes did not differ from controls or STP (p≥0.661; χ²≤0.829). Positive correlations between MYLK1 copy number and strength and power performance were detected. Individuals with three copies were able to produce more power in isokinetic tests, jump higher and sprint faster than individuals with two copies in the whole cohort and these correlations were stronger in the STP. The strongest correlations found were with MYLK copy number and isokinetic flexion of the arm in STP (p=0.003, R²=7.78). MYLK-AS1 did not associate with athlete status or measures of athletic performance (p>0.05). The improvements in performance with increased copy number indicate that copy number variants are associated with improved skeletal muscle phenotypes. These results, further current knowledge of how genetic variants underpin muscle phenotypes and indicate that MYLK1 potentially could be used as a target for improvements in athletic performance and treatment of muscle wasting disorders.