What you carry at this position in your DNA and what research says about it.
Blood Calcium Levels: 10/10 evidence, 26 publications.
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Sample genotype (not yours): G/G
Typical Blood Calcium Levels
Baseline blood calcium and phosphate levels are typical with this common genetic profile.
What this genotype means: Typical baseline blood calcium levels; Slightly higher blood phosphate levels; Standard calcium-sensing receptor sensitivity.
Sample genotype (not yours): G/T
Slightly Higher Baseline Blood Calcium
A single copy of the T allele is associated with a very mild, harmless increase in baseline blood calcium levels.
What this genotype means: Slightly higher baseline blood calcium; Slightly lower baseline blood phosphate; Normal physiological variation.
Sample genotype (not yours): T/T
Higher Baseline Blood Calcium
Two copies of the T allele are associated with slightly higher baseline blood calcium levels within a healthy range.
What this genotype means: Higher baseline blood calcium within normal limits; Slightly lower baseline blood phosphate; Completely benign physiological profile.
Gene function and biological role
Gene Function: The CASR gene encodes the calcium-sensing receptor, a protein that plays a central role in maintaining calcium homeostasis [1]. It is primarily expressed in the parathyroid glands and kidneys, where it monitors the concentration of extracellular calcium ions [2]. When calcium levels rise, the receptor is activated, which suppresses the secretion of parathyroid hormone [1]. This suppression reduces calcium release from bones and increases calcium excretion in the urine [1]. Through these feedback loops, the receptor ensures that blood calcium remains within a narrow, healthy range [1].
Variant Impact: The rs1801725 variant is a missense mutation in exon 7 of the CASR gene that changes the amino acid at position 986 from alanine to serine [1]. This change occurs in the intracellular carboxyl-terminal tail of the receptor, slightly reducing its sensitivity to calcium [3]. As a result, the receptor requires slightly higher levels of calcium in the blood to trigger its feedback mechanisms [3]. This leads to a mild, lifelong shift in baseline blood calcium levels [4]. Despite this shift, clinical evaluations have determined that this common variation is completely benign and does not cause calcium-related disorders [5].
Key Insight: This variant acts like a tiny adjustment to your body's internal thermostat for calcium, slightly shifting your baseline levels without causing health problems.
Location: CASR. Chromosome 3 · 3q21.1 · 122.3 Mb
Estimated prevalence by population
Global 79.5%; European 73.9%; African 93.1%; East Asian 93.8%; South Asian 66.8%; Americas 77.2%; Ashkenazi 54.3%; Finnish 74.5%; Middle Eastern 54.5%; Amish 81.6%.
Estimated GG genotype frequency.
Global 19.0%; European 24.2%; African 6.8%; East Asian 6.1%; South Asian 29.9%; Americas 21.3%; Ashkenazi 38.8%; Finnish 23.6%; Middle Eastern 38.7%; Amish 17.4%.
Estimated GT genotype frequency.
Global 1.5%; European 2.0%; African 0.1%; East Asian 0.1%; South Asian 3.3%; Americas 1.5%; Ashkenazi 6.9%; Finnish 1.9%; Middle Eastern 6.9%; Amish 0.9%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Nutrition & Metabolism
Blood Chemistry & Metabolites
Blood Calcium Levels. Evidence: 10/10. Source: PMID 20661308. Typical.
Blood Phosphate Levels. Evidence: 10/10. Source: PMID 33462484. Slightly Higher.
Cardiovascular & Metabolic
Heart Rhythm & Conduction
QT Interval. Evidence: 8/10. Source: PMID 29874175. Slightly Longer.
Organ Systems
Bone, Joint & Connective Tissue Health
Bone Mineral Density. Evidence: 7/10. Source: PMID 11248745. Typical.
Showing effects for G/T genotype
Blood Calcium Levels. Evidence: 10/10. Source: PMID 20661308. Slightly Higher.
Blood Phosphate Levels. Evidence: 10/10. Source: PMID 33462484. Typical.
QT Interval. Evidence: 8/10. Source: PMID 29874175. Typical.
Showing effects for T/T genotype
Blood Calcium Levels. Evidence: 10/10. Source: PMID 20661308. Higher.
Blood Phosphate Levels. Evidence: 10/10. Source: PMID 33462484. Slightly Lower.
QT Interval. Evidence: 8/10. Source: PMID 29874175. Slightly Shorter.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Two copies of the G allele mean the calcium-sensing receptor operates at its standard sensitivity level [1]. Baseline blood calcium levels are typically in the standard range [2]. This genotype is also associated with slightly higher blood phosphate levels and a marginally longer heart QT interval compared to carriers of the T allele [3] [4]. However, all of these measurements generally remain well within normal, healthy physiological limits [2]. Clinical databases classify this common genetic profile as completely benign, with no association to calcium-related disorders [5]. No special dietary changes or medical monitoring are recommended based on this genotype.
Typical baseline blood calcium levels; Slightly higher blood phosphate levels; Standard calcium-sensing receptor sensitivity.
Sample genotype: GT (Heterozygous)
One copy of the T allele slightly reduces the sensitivity of the calcium-sensing receptor [1]. As a result, the body maintains baseline blood calcium levels that are marginally higher than those with the typical G/G genotype [2]. This shift is very small, averaging less than 0.1 mmol/L, and remains within the normal clinical range [2]. It is also associated with slightly lower blood phosphate levels and a marginally shorter heart QT interval [3] [4]. Clinical studies and genetic databases have confirmed that this variation is completely benign and does not increase the risk of kidney stones or parathyroid disorders [5]. It represents a normal physiological variation rather than a medical concern.
Slightly higher baseline blood calcium; Slightly lower baseline blood phosphate; Normal physiological variation.
Sample genotype: TT (Homozygous)
Two copies of the T allele lead to a mild reduction in the sensitivity of the calcium-sensing receptor [1]. The body compensates by establishing a baseline blood calcium level that is slightly higher than average [2]. This genetic shift is physiological and typically stays within the normal clinical range [2]. It is also linked to slightly lower blood phosphate levels and a marginally shorter heart QT interval [3] [4]. Multiple clinical evaluations have confirmed that this genotype is entirely harmless and does not cause hypercalcemia or other parathyroid conditions [5]. It is simply a reflection of natural human genetic diversity.
Higher baseline blood calcium within normal limits; Slightly lower baseline blood phosphate; Completely benign physiological profile.
Variants with shared genetic architecture
rs1042636 · CASR Gene · Chr 3 · Kidney Stone Risk
rs6013897 · BCAS1 Gene · Chr 20 · Vitamin D and Bone Health
rs11153730 · PLN Gene · Chr 6 · QT Interval Duration
A986S polymorphism of the calcium-sensing receptor and circulating calcium concentrations.
Genetics of 35 blood and urine biomarkers in the UK Biobank.
Content updated August 2026.
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