mtDNA and ACTN3 of Finnish athletes

The ACTN3 genotype was previously associated with athletic performance. Individuals who are homozygous RR (wild-type) tend to excel in sprints, while those who are XX tend to excel in endurance. According to ACTN3 Genotype Is Associated with Human Elite Athletic Performance:

In addition, the frequency of the α-actinin-3–deficient genotype (577XX) varies from 25% in Asian populations to <1%>
A new study has investigated the ACTN3 genotypes in Finnish athletes, and has also studied their mtDNA composition. It turns out that two haplogroups (J2 and K) are lacking in endurance athletes.

European Journal of Human Genetics (advance online publication)

Mitochondrial DNA and ACTN3 genotypes in Finnish elite endurance and sprint athletes
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Anna-Kaisa Niemi and Kari Majamaa

Abstract

Differences in ACTN3 (alpha-actinin 3) genotypes have been reported among endurance and power athletes. Elite athletic performance in endurance sports should also depend on mitochondrial oxidative phosphorylation (OXPHOS) that produces ATP for muscle metabolism. We determined mitochondrial DNA (mtDNA) and ACTN3 genotypes in Finnish elite endurance (n=52) and sprint (n=89) athletes, and found that the frequencies of mtDNA haplogroups differed significantly between the two groups. Most notably, none of the endurance athletes belonged to haplogroup K or subhaplogroup J2, both of which have previously been associated with longevity. The frequency of ACTN3 XX genotype was higher and that of RR was lower among Finnish endurance athletes, and, in addition, none of the top Finnish sprinters had the XX genotype. Lack of mtDNA haplogroup K and subhaplogroup J2 among elite endurance athletes suggests that these haplogroups are 'uncoupling genomes'. Such genomes should not be beneficial to endurance-type athletic performance but should be beneficial to longevity, since uncoupling of OXPHOS reduces the production of ATP, reduces the release of reactive oxygen species and generates heat.

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