The Effect of Heterozygosity for the ACTN3 Null Allele on Human Muscle Performance

Abstract

α-Actinin-3 is primarily expressed in fast (Type II) fibers in the human skeletal muscle. Over 70% of the global population has at least one copy of a loss of function allele because of a premature stop codon in the ACTN3 gene (R577X). Homozygosity for this variant (577XX) occurs in approximately 16% of humans worldwide and results in complete α-actinin-3 deficiency, which is detrimental to sprint/power performance and alters adaptation to changing physical demands. The functional implications of α-actinin-3 deficiency have been the infject of over 90 studies; however, the effect of heterozygosity for the ACTN3 null allele is not well documented or understood. Purpose We reviewed the literat..