What you carry at this position in your DNA and what research says about it.
Muscle and Kidney Function: 9/10 evidence, 24 publications.
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Sample genotype (not yours): G/G
Higher Muscle Mass and Stronger Lung Function
This genotype is linked to greater physical strength, higher lean muscle tissue, and robust lung capacity.
What this genotype means: Greater lean muscle mass; Stronger physical grip strength; Higher respiratory vital capacity.
Sample genotype (not yours): A/A
Higher Kidney Filtration but Lower Muscle Mass
This genotype presents a trade-off, featuring enhanced kidney filtration alongside lower muscle mass and lung capacity.
What this genotype means: Enhanced kidney filtration rate; Lower lean muscle mass and grip strength; Slightly higher tendency for abdominal fat.
Sample genotype (not yours): G/A
Typical Muscle Mass and Kidney Function
This genotype represents a balanced genetic profile with typical muscle strength and standard kidney filtration rates.
What this genotype means: Standard muscle mass and grip strength; Typical respiratory capacity; Normal kidney filtration rates.
Gene function and biological role
Gene Function: The CACNA1S gene encodes the alpha-1S subunit of the dihydropyridine receptor, a critical voltage-gated calcium channel in skeletal muscle [1]. This protein acts as a voltage sensor, translating electrical signals from the nervous system into physical muscle contraction [1]. Proper functioning of this channel is essential for maintaining muscle tone, strength, and overall excitation-contraction coupling [2]. Variants in this gene are historically studied for their roles in rare muscle-weakness disorders and sensitivity to certain anesthetics [1]. However, common variations in CACNA1S also influence everyday physical traits like muscle volume and grip strength across the general population [2].
Variant Impact: The rs3850625 variant is a missense mutation in the CACNA1S gene that alters the encoded protein sequence [3]. Specifically, it causes an amino acid substitution where arginine is replaced by cysteine at position 1539 of the calcium channel subunit [3]. This structural alteration is located in a key functional domain of the channel, subtly modifying how calcium ions flow during muscle activation [3]. While ClinVar database submissions confirm this specific change is benign and does not cause severe genetic myopathies, it acts as a genetic dial for systemic traits [3]. Through its influence on calcium signaling, the variant impacts muscle development, lung capacity, and metabolic markers like kidney filtration [4].
Read on the Thigh Muscle Volume page
Key Insight: This single genetic change acts as a biological trade-off, balancing physical muscle performance and lung capacity against the rate at which the kidneys filter waste.
Location: CACNA1S. Chromosome 1 · 1q32.1 · 201.0 Mb
Estimated prevalence by population
Global 83.0%; European 77.4%; African 95.8%; East Asian 92.8%; South Asian 65.1%; Americas 84.5%; Ashkenazi 82.5%; Finnish 72.6%; Middle Eastern 90.7%; Amish 54.5%.
Estimated GG genotype frequency.
Global 15.9%; European 21.2%; African 4.2%; East Asian 7.1%; South Asian 31.2%; Americas 14.8%; Ashkenazi 16.6%; Finnish 25.2%; Middle Eastern 9.1%; Amish 38.6%.
Estimated GA genotype frequency.
Global 1.1%; European 1.4%; African < 0.1%; East Asian 0.1%; South Asian 3.7%; Americas 0.6%; Ashkenazi 0.8%; Finnish 2.2%; Middle Eastern 0.2%; Amish 6.8%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Organ Systems
Kidney Function & Disease
Kidney Function. Evidence: 9/10. Source: PMID 26831199. Typical.
Respiratory Health
Lung Function. Evidence: 8/10. Source: PMID 30595370. Higher Capacity.
Lifestyle, Fitness & Aging
Muscle Strength & Power
Muscle Strength. Evidence: 9/10. Source: PMID 33097823. Higher.
Cardiovascular & Metabolic
Obesity & Body Composition
Abdominal Fat. Evidence: 6/10. Source: PMID 35773277. Lower.
Showing effects for A/A genotype
Kidney Function. Evidence: 9/10. Source: PMID 26831199. ~0.66 mL/min Higher.
Lung Function. Evidence: 8/10. Source: PMID 30595370. Lower Capacity.
Muscle Strength. Evidence: 9/10. Source: PMID 33097823. Lower.
Abdominal Fat. Evidence: 6/10. Source: PMID 35773277. Higher.
Showing effects for G/A genotype
Kidney Function. Evidence: 9/10. Source: PMID 26831199. Slightly Higher.
Lung Function. Evidence: 8/10. Source: PMID 30595370. Typical.
Muscle Strength. Evidence: 9/10. Source: PMID 33097823. Typical.
Abdominal Fat. Evidence: 6/10. Source: PMID 35773277. Typical.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Having two copies of the G allele is associated with optimal calcium channel function in skeletal muscle tissue. Large-scale genomic studies show that this translates to higher overall grip strength and increased thigh muscle volume [1]. Individuals with this profile also tend to exhibit greater vital capacity, indicating stronger lung function and respiratory muscle efficiency [2]. On the metabolic side, this genotype is linked to lower levels of abdominal fat accumulation [3]. While kidney filtration rates are typical rather than elevated, overall physical and respiratory metrics are highly favorable [4].
Greater lean muscle mass; Stronger physical grip strength; Higher respiratory vital capacity.
Sample genotype: AA (Homozygous)
Having two copies of the A allele alters calcium channel dynamics, leading to a distinct physiological trade-off. On the positive side, this profile is associated with a significantly higher estimated glomerular filtration rate, indicating efficient kidney function [1]. However, this comes with a tendency toward lower lean muscle mass, reduced thigh muscle volume, and weaker grip strength [2]. Lung function parameters, such as vital capacity, also tend to be lower compared to other genotypes [3]. Additionally, studies link this genetic profile to a higher accumulation of abdominal fat and a slightly increased susceptibility to skeletal variations [4].
Enhanced kidney filtration rate; Lower lean muscle mass and grip strength; Slightly higher tendency for abdominal fat.
Sample genotype: GA (Heterozygous)
Carrying one G allele and one A allele results in an intermediate physical and metabolic profile. Calcium signaling in skeletal muscles operates at a standard baseline, supporting typical muscle mass and grip strength [1]. Lung capacity and respiratory vital capacity also fall within the normal, expected range for the population [2]. On the metabolic front, kidney filtration rates are slightly higher than the baseline but remain thoroughly typical [3]. There are no elevated risks for skeletal abnormalities or unusual abdominal fat accumulation associated with this balanced genetic makeup [4].
Standard muscle mass and grip strength; Typical respiratory capacity; Normal kidney filtration rates.
Variants with shared genetic architecture
rs28930069 · CACNA1S Gene · Chr 1 · Periodic Paralysis Risk
rs80338777 · CACNA1S Gene · Chr 1 · Periodic Paralysis Risk
rs12258967 · CACNB2 Gene · Chr 10 · Blood Pressure
A scalable variational inference approach for increased mixed-model association power.
Inherited basis of visceral, abdominal subcutaneous and gluteofemoral fat depots.
A catalog of genetic loci associated with kidney function from analyses of a million individuals.
Content updated August 2026.
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