What is the function of the ACTN3 gene? Is it true that your ACTN3 genotype determines your running ability? <\/p>\n\n\n\n
ACTN3 hosts the code for making the protein called Alpha-actinin-3. The \u201cR variant\u201d of the gene results in normal production of the protein, but the \u201cX\u201d variant prevents the protein from being synthesized. While scientists do not know how this happens, there’s a strong correlation between the R genotype and sprinting speed. Tests on athletes from around the world have revealed that the XX genotype is almost nowhere to be found in elite sprinters.<\/p>\n\n\n\n
Keep reading to learn why the ACTN3 gene is called the “speed gene” or the “sprinter gene.”<\/p>\n\n\n\n\n\n\n\n
The ACTN3 gene encodes the Alpha-actinin-3 protein, which is found in fast-twitch muscle fibers. Our ratio of fast- to slow-twitch muscle fibers can determine our success in certain sports.<\/p>\n\n\n\n
Researchers following the ACTN3 gene found that almost all African people (and people with recent African heritage) have at least one \u201cR\u201d copy of the gene. In contrast, populations from other parts of the world have varying frequencies of X alleles (for example, 25% of people of East Asian ancestry had two X copies). One possible explanation is that having less muscle mass is more efficient for metabolism in cold climates. Another is that the shift from hunting and gathering to agriculture meant that people were less dependent on bursts of speed and worked less intensely for a longer period of time, which would favor slow-twitch muscle fibers. <\/p>\n\n\n\n
The lack of a scientific explanation for why the XX variant is virtually absent in elite sprinters has not stopped for-profit genetic testing companies from selling genetic tests for ACTN3 gene variants to interested athletes and parents. As Epstein points out, since we do not know why some athletes are naturally fast, these tests can only really serve to add further evidence to the fact that most people with the XX genotype will not become elite sprinters; a fact that most people can ascertain without genetic testing. <\/p>\n\n\n\n