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Re: ACTN3 was never ‘the’ gene for speed

Dear Editor,

Lucia and colleagues [1] recently reported a case study in which a Spanish elite long jumper was identified as being α-actinin-3 deficient, owing to carrying the X/X genotype of the R577X polymorphism in the ACTN3 gene. The authors suggest that the case provides a “notable” exception to the idea that ACTN3 represents “the ‘gene for speed’,” taking out of context a question posed in a recent review by MacArthur and North [2]. In their review, MacArthur and North consider the evidence for ACTN3 as ‘a’ potential gene important for muscle power performance, and in fact emphasize the “subtle effect” and “apparent benefit” for the gene on performance. Such words reflect the fact that muscle power and power- related performance are undoubtedly highly complex traits, governed by multiple genetic and environmental factors [3]. That ACTN3 may be a contributing gene for speed/power is certainly supported by several studies [4]. A notable feature of the present case is that it is the only elite-level strength or power athlete reported to date to be α- actinin-3 deficient [5, 6], providing indirect support for the hypothesis that α-actinin-3 is an important contributor to muscle power performance.

Stephen M. Roth, Ph.D. Department of Kinesiology University of Maryland College Park, MD 20742

References

1. Lucia, A, J Olivan, F Gomez-Gallego, C Santiago, M Montil, and C Foster. Citius and longius (faster and longer) with no alpha- actinin-3 in skeletal muscles? Br J Sports Med 2007; 41: 616-617.

2. MacArthur, DG and KN North. A gene for speed? The evolution and function of alpha-actinin-3. Bioessays 2004; 26(7): 786-95.

3. Beunen, G and M Thomis. Gene powered? Where to go from heritability (h2) in muscle strength and power? Exerc Sport Sci Rev 2004; 32(4): 148-54.

4. MacArthur, DG and KN North. ACTN3: A genetic influence on muscle function and athletic performance. Exerc Sport Sci Rev 2007; 35(1): 30-4.

5. Yang, N, DG MacArthur, JP Gulbin, AG Hahn, AH Beggs, S Easteal, et al. ACTN3 genotype is associated with human elite athletic performance. Am.J.Hum.Genet. 2003; 73: 627-631.

6. Niemi, AK and K Majamaa. Mitochondrial DNA and ACTN3 genotypes in Finnish elite endurance and sprint athletes. Eur J Hum Genet 2005; 13(8): 965-9.