Your result, the one DNA position behind it, and what the research says.
7/10 confidence.
CACNA1S is the voltage sensor in skeletal muscle: it is the switch that turns a nerve signal into the calcium release that makes a fiber contract. A study that measured thigh muscle volume by imaging, rather than estimating it, picked this position up. Imaging studies are small but they measure the thing itself, which is worth more than a questionnaire. Training still decides most of muscle volume.
Good to know: This comes from a single imaging study rather than a questionnaire, which is a point in its favor. Training and inheritance both shape muscle volume, and this single position accounts for very little of it. Only about a fifth of readers carry a copy at all.
Fun fact: CACNA1S acts as a mechanical switch rather than a normal ion channel: it physically nudges a second channel to release the calcium that makes muscle contract.
Discovery: Thigh muscle volume was mapped in an imaging-based genome-wide study.
The single variant behind this trait
Gene: CACNA1S
Location: Chr 1:201,047,168
dbSNP rs3850625
Content updated September 2026.
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