CASR rs193922420: Understanding Calcium Homeostasis Variants
The rs193922420 variant is located within the CASR gene, which provides instructions for the calcium-sensing receptor. This variant is studied for its potential role in disorders of calcium homeostasis, such as familial hypocalciuric hypercalcemia and autosomal dominant hypocalcemia.
What each genotype means
Typical calcium sensing receptor
This is the common, expected genotype for this position in the CASR gene. It is considered the reference sequence and is not associated with the calcium-related disorders linked to this variant.
This is the most common genotype found in the general population.
Potential calcium regulation variant
This genotype indicates you carry one copy of the variant allele. Research has linked this specific change to familial hypocalciuric hypercalcemia, a condition that can affect how your body regulates calcium levels. Please consult with a healthcare provider to discuss if this finding is clinically relevant to your health history.
This genotype is rare in the general population.
Increased risk for hypercalcemia
This genotype indicates you carry two copies of the variant allele, which has been classified as likely pathogenic in clinical databases. This variant is associated with familial hypocalciuric hypercalcemia, a condition characterized by higher than normal levels of calcium in the blood. You should discuss these results with a physician or genetic counselor to determine if further clinical testing or monitoring is appropriate.
This genotype is very rare in the general population.
What is rs193922420?
The rs193922420 variant is a specific single nucleotide polymorphism (SNP) found within the CASR gene. In genomics, a SNP represents a variation at a single position in the DNA sequence among individuals. The CASR gene is located on chromosome 3 and is responsible for encoding the calcium-sensing receptor (CaSR) protein. This protein acts as a critical sensor for extracellular calcium levels in the body. Because the CaSR protein is expressed in various tissues, including the parathyroid glands and the kidneys, variations in the gene sequence can potentially alter how the body detects and responds to calcium concentrations. Researchers track these specific variants to understand how they might influence the sensitivity of the 'calciostat' mechanism, which maintains the tight regulation of serum calcium levels necessary for normal physiological function.
The Role of the CASR Gene
The CASR gene encodes the calcium-sensing receptor, a G-protein-coupled receptor that functions as a primary regulator of systemic calcium homeostasis. By monitoring the concentration of ionized calcium in the extracellular fluid, the CaSR protein allows the parathyroid glands to adjust the secretion of parathyroid hormone (PTH) accordingly. When calcium levels are high, the receptor signals to suppress PTH release; when levels are low, it triggers an increase in PTH to help restore balance. Beyond the parathyroid glands, the receptor is active in the kidneys, where it influences how much calcium is reabsorbed or excreted in urine. Because of its central role in mineral metabolism, the CASR gene is a focal point for research into conditions where calcium levels are abnormally high or low, as even minor changes in receptor sensitivity can have systemic effects.
Research and Clinical Associations
Scientific research has established that variants in the CASR gene are linked to several disorders of calcium homeostasis. Loss-of-function variants are typically associated with familial hypocalciuric hypercalcemia (FHH), a condition characterized by elevated blood calcium levels, while gain-of-function variants are associated with autosomal dominant hypocalcemia (ADH), which leads to low blood calcium. The evidence for the clinical significance of specific variants like rs193922420 is often categorized based on functional studies and clinical observations. It is important to note that the impact of any single variant can be complex, and not all variants identified in the CASR gene result in clinical disease. Current research continues to evaluate the pathogenicity of rare variants, and findings are often updated in public databases as more clinical data becomes available. Genetic associations are statistical in nature and do not serve as a medical diagnosis.
Population Frequency and Interpretation
The rs193922420 variant is classified as rare in the general population. In genomics, 'rare' typically indicates that the variant is found in a very small percentage of individuals across diverse ancestral groups. Because it is rare, large-scale population studies may have limited data regarding its specific distribution or its exact phenotypic impact across different ethnicities. When interpreting genetic information, it is essential to recognize that the presence of a rare variant does not automatically imply a health condition. Many rare variants are benign and have no observable effect on health. Readers should view this information as a tool for understanding their genetic makeup rather than a definitive health assessment. If you have concerns about your calcium levels or family history, it is recommended to consult with a healthcare professional or a genetic counselor who can provide context based on your personal medical history.
What You Can Do With This Information
Genetic information regarding variants like rs193922420 is primarily educational. You cannot use this information to diagnose yourself or others with a medical condition. If you have received a report indicating you carry this variant, the most appropriate step is to discuss the findings with a qualified clinician, such as an endocrinologist or a primary care physician. They can interpret the result in the context of your actual blood calcium levels and clinical symptoms. Avoid making any changes to your diet, supplements, or medications based solely on genetic data. If you are currently taking medications that affect calcium metabolism, always consult your pharmacist or doctor before making any adjustments. Genetic testing provides a piece of the puzzle, but clinical laboratory tests, such as serum calcium and PTH measurements, remain the gold standard for assessing your health status.
How common is this variant?
The rs193922420 variant is considered rare across global populations, meaning it is found in only a very small fraction of the general population.
Frequently asked questions
What does it mean if I have a rare CASR variant?
Having a rare variant in the CASR gene does not necessarily mean you have a health condition. Many rare variants are benign, and clinical significance is determined by a combination of genetic testing and physical blood work.
Can this variant cause high calcium levels?
Some variants in the CASR gene are associated with familial hypocalciuric hypercalcemia, which causes high blood calcium. However, whether this specific variant causes such an effect requires clinical evaluation by a doctor.
Should I change my diet if I have this variant?
No, you should not change your diet or calcium intake based on a genetic variant. Always consult with a healthcare provider before making any changes to your nutrition or supplement regimen.
How do I know if this variant is affecting my health?
The only way to know if your calcium homeostasis is affected is through clinical blood tests, such as serum calcium and parathyroid hormone levels. A genetic variant is just one piece of information that a doctor uses alongside your medical history.
Where can I find more information about CASR?
You can find reliable information on the CASR gene through resources like MedlinePlus Genetics or the NCBI Gene database. These sites provide comprehensive overviews of gene functions and associated conditions.
Sources & further reading
Educational information only, last refreshed 9/18/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs193922420?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29Related variants in CASR
Variant in the CASR gene, which encodes the calcium-sensing receptor critical for systemic calcium homeostasis.
Variant in the CASR gene involved in the regulation of the calcium-sensing receptor.
Variant in the CASR gene associated with altered calcium-sensing receptor sensitivity and regulation of parathyroid hormone secretion.
Pathogenic missense variant causing familial hypocalciuric hypercalcemia type 1 (FHH1).
Variant in the CASR gene associated with the calcium-sensing receptor protein.