CASR: The Calcium Gene
The Calcium sensing receptor (CASR) gene is associated with the synthesis of Calcium sensing receptor, a receptor that binds to calcium present in the blood.
Specific alleles of this gene are known to either increase or decrease the sensitivity to calcium.
Variants of the gene are shown to be associated with the levels of Calcium, Magnesium, and Phosphate in the blood.
There are two single nucleotide polymorphisms that have an association with this gene; rs17251221 and rs1801725.
The CASR protein is present on the cells of the parathyroid glands, which are associated with the secretion of the parathyroid hormone.
This hormone transfers calcium from the bone into the blood, with bones acting as storage centers for calcium.
When calcium levels are high, the level of parathyroid hormone are low.
This facilitates increased binding of calcium to CASR receptors in kidney.
This ultimately leads to more removal of calcium via kidneys.
Does your 23andMe, Ancestry DNA, FTDNA raw data have CASR gene variant information?
| CHIP Version | CASR SNPs |
| 23andMe (Use your 23andme raw data to know your CASR Variant) | |
| v1 23andme | Present |
| v2 23andme | Present |
| v3 23andme | Present |
| v4 23andme | Present |
| V5 23andme (current chip) | Present |
| AncestryDNA (Use your ancestry DNA raw data to know your CASR Variant) | |
| v1 ancestry DNA | Present |
| V2 ancestry DNA (current chip) | Present |
| Family Tree DNA (Use your FTDNA raw data to know your CASR Variant) | |
| OmniExpress microarray chip | Present |
Association with Calcium Levels
In a genome wide association study, it was found that the SNP rs1801725 had a strong association with people of European descent while the SNP rs17251221 had a strong association with people of Indian Asian descent. These two SNPs are found to be in high linkage disequilibrium with each other. Another study showed that people with the G variant (rs17251221) of the gene were associated with increased calcium levels. Each copy of the G allele increases Calcium levels by 0.06 mg/dl.
Association with Magnesium Levels
People with the G variant (rs17251221) of the gene were associated increased magnesium levels in the serum.
Association with Phosphate Levels
People with the G (rs17251221) variant of the gene are shown to be associated with decreased Phosphate level in the serum. Increased secretion of the parathyroid hormone which results in elevated calcium levels is associated with decreased phosphate levels due to the phosphaturic effect.
Association with multiplicity in calcium nephrothiliasis
People with the G variant were associated with a higher risk of stone multiplicity.
How can this information be used?
It is important to choose an appropriate diet based on the genetic profile.
| For people with G (rs17251221) Likely to have increased serum calcium and serum magnesium level. Likely to have decreased serum phosphate level Include 600mg/day of phosphorous from pumpkin seeds, salmon, brazil nuts and shellfish. |
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| For people with A variant (rs17251221) Likely to have decreased serum calcium and serum magnesium levels Likely to have increased serum phosphate levels Include 40-500mg of calcium per day |
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| For people with T (rs1801725) Likely to have increased serum calcium level |
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| For people with G variant (rs1801725) Likely to have decreased serum calcium Include 40-500mg of calcium per day |
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References:
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908705/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951868/
- http://csg.sph.umich.edu/yli/publications/pdf/20Kapur2010.pdf
- https://www.semanticscholar.org/paper/A-Genetic-Polymorphism-rs17251221-in-the-Calcium-Chou Woon/82bb4ed6982b322b4f8f58ac982ff6fba988ecbb
