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Know Your Genes: CASR – “The Calcium Gene”

Serum Calcium Level
Serum Phosphate Level
Serum Magnesium Level
Multiplicity of stones (Calcium nephrothiliasis)

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 associated 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 is lowered and there is increased removal of calcium via kidneys, modulated by increased binding of calcium to the CASR receptor on the kidney cells.

Association with Calcium Level:

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 in the body:

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.

Genotype

(rs17251221)

Phenotype
AA
  • [Limitation] More likely to have decreased serum calcium level
  • [Limitation] More likely to have decreased serum magnesium level
  • [Advantage] More likely to have increased serum phosphate level
AG
  • Moderate serum calcium level
GG
  • [Advantage] More likely to have increased serum calcium level
  • [Advantage] More likely to have increased serum magnesium level
  • [Limitation] More likely to have decreased serum phosphate level

 

Genotype

(rs1801725)

Phenotype
TT
  • [Advantage] More likely to significantly increased serum calcium level
GT
  • Moderate serum calcium level
GG
  • [Limitation] More likely to have decreased serum calcium level

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. 

 

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

 

For people with T (rs1801725)

  • Likely to have increased serum calcium level

 

For people with G variant (rs1801725)

  • Likely to have decreased serum calcium
  • Include 40-500mg of calcium per day

References:

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908705/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951868/
  3. http://csg.sph.umich.edu/yli/publications/pdf/20Kapur2010.pdf
  4. https://www.semanticscholar.org/paper/A-Genetic-Polymorphism-rs17251221-in-the-Calcium-Chou Woon/82bb4ed6982b322b4f8f58ac982ff6fba988ecbb
Find out which variation of the gene you carry and more at www.xcode.in

Nutrigenetics, fitness genetics, health genetics are all nascent but rapidly growing areas within human genetics. The information provided herein is based on preliminary scientific studies and it is to be read and understood in that context.”

Amrita Surendranath
Amrita Surendranath
Amrita has a Masters in Human Genetics which fuelled her passion for genes and their diktats. She loves converting genetic research into exciting scientific news with a punch. 10 years on, her interesting insights have covered a range of topics that include cancer, diabetes, nutrition, fitness and more. A pulse on what’s interesting aids in decoding laboratory data into useful science that could empower people into molding healthier lifestyles.