What this means

ACE (angiotensin-converting enzyme) has a famous insertion/deletion polymorphism in intron 16 that comes in two flavours: I (insertion, lower enzyme activity) and D (deletion, higher activity). The classic I/D variant is not on most SNP chips, so rs4341 is commonly used as a proxy — it sits very close and tracks the I/D status well. The I allele is slightly enriched among elite endurance athletes and the D allele among power athletes, but as with ACTN3 the effect size is small enough that training matters far more than genotype.

The ACE gene comes in two flavours: one version makes a slightly less active enzyme, the other makes a more active one. The less-active form shows up a bit more often in elite endurance athletes (distance runners, rowers, climbers) and the more-active form shows up a bit more often in elite sprinters and power athletes. The test here looks at a nearby DNA spot that tracks the original variant well. The effect is small though — training, technique, and how much you sleep matter far more than which version you happen to carry.

Caveats

• rs4341 is a proxy for the actual I/D polymorphism — accuracy is high but not perfect.
• The effect is statistical and small; many elite athletes carry the "wrong" genotype.
• Not a useful guide to choosing a sport for any individual.
• Most evidence comes from European-ancestry cohorts.

References

• Montgomery et al. — Human gene for physical performance (Nature, 1998)
• Ma et al. — The association of sport performance with ACE and ACTN3 genetic polymorphisms: a systematic review and meta-analysis (PLOS ONE, 2013)