ACTN3 R577X Polymorphism in Asian Indian Athletes

Replacement of Arginine (R) by a premature stop codon (X) (R577X, rs1815739) in Alpha-actinin 3 gene (ACTN3) has been commonly reported. The R allele has been hypothesized to be associated with power-based performance, while the X allele may be linked with endurance abilities. To evaluate if this theory holds true in Indian subjects, we studied the ACTN3 genotype distribution in 305 Asian Indians, comprising of 155 athletes and 150 normal sedentary individuals. We did not observe any significant difference in the allelic frequencies between athletes (R/X=0.42/0.58) and normal subjects ((R/X=0.39/0.61). But, while categorizing the athletes on the basis of their competitive level (National/International vs. Regional); the genotype distribution pattern became more prominent (chi(2) = 4.9, d.f=2, p=0.08), though not statistically significant. Additionally, in the National/International athletes, R allele was seen to be associated with power based performance (chi(2) = 6.6, d.f=1, p<0.01). In the same group, a high frequency of X allele was observed with endurance performance (chi(2)=3.14, d.f=1, p=0.07), but fell short of significance. Thus, XX genotype could be an important factor in determining endurance performance. However, the study needs to be expanded to a larger cohort of National/International athletes. To our information, this is the first Indian study on ACTN3 genotype and its association with sporting performance.