The α-actinin-3 (
ACTN3) gene encodes a Z-disc structural protein which is found only in fast glycolytic muscle fibers. A common nonsense polymorphism
in codon 577 of the
ACTN3 gene (R577X) results in α-actinin-3 deficiency in XX homozygotes. Previous reports have shown a lower proportion of the
ACTN3 XX genotype in power-oriented athletes compared to the general population. In the present study we tested whether XX genotype
was under-represented in Russian power-oriented athletes. The study involved 486 Russian power-oriented athletes of regional
or national competitive standard.
ACTN3 genotype and allele frequencies were compared to 1,197 controls. The frequencies of the
ACTN3 XX genotype (6.4 vs. 14.2%;
P < 0.0001) and X allele (33.3 vs. 38.7%;
P = 0.004) were significantly lower in power-oriented athletes compared to controls. Furthermore, the lowest (3.4%) frequency
of the
ACTN3 XX genotype was found in a group of highly elite athletes, supporting the hypothesis that the presence of α-actinin-3 has
a beneficial effect on the function of skeletal muscle in generating forceful contractions at high velocity. In conclusion,
ACTN3 R577X polymorphism was associated with power athlete status in Russians.
Keywords α-actinin-3 - Genotype - Fast-twitch fibers - Power performance