A gene for speed : the influence of ACTN3 on muscle performance in health and disease

α-Actinin-3 is a fast fibre Z-line protein that interacts with a wide array of structural, metabolic and signalling proteins. A common ACTN3 null polymorphism (R577X) is the most widely studied and best replicated genetic variant known to influence the skeletal muscle performance. ACTN3 genotype contributes ~2.5% of the variance in human muscle strength and exercise training response, is a risk factor for falling in the elderly and a genetic modifier of muscle disorders such as Duchenne muscular dystrophy