The CASR gene helps your parathyroid glands and kidneys sense calcium in the blood and keep it in balance. If it does not work properly, calcium levels can become too high or too low, which may lead to kidney stones, muscle cramps, tingling, or seizures. This gene plays an important role in helping your body adjust parathyroid hormone, a key signal for calcium control. Some inherited variants in the CASR gene are linked to mild inherited high blood calcium or to forms of low blood calcium.
What is a gene?
Genes are stretches of DNA that give your cells instructions for making molecules or regulating processes in the body. Some genes carry the code for proteins, the parts of cells that do the work. Other genes mainly control when certain processes happen, where they happen, and how strongly they operate. Together, genes affect how the body develops and functions, and they can influence how you respond to food, stress, or medications. To explore this topic in more detail, you can learn more in the LearnHub.
Overview
CASRGene function
What if the gene works
The CASR gene helps cells sense calcium levels in the blood. This supports healthy control of parathyroid hormone and helps the kidneys and parathyroid glands keep calcium balance steady.
Risk
What if the gene does not work
Variants in the CASR gene can upset calcium sensing, causing high blood calcium with low urine calcium or, less often, low blood calcium. Milder or more severe variants may affect when symptoms appear and how marked they are.
Treatment
What does that mean for your treatment
With a pathogenic loss-of-function variant in the CASR gene, mild familial hypocalciuric hypercalcemia usually does not need treatment, and parathyroid surgery is generally not helpful. If calcium levels cause symptoms or are much higher, cinacalcet can help some people with CASR-related hypercalcemia. Severe newborn presentations may need urgent specialist treatment, sometimes including surgery.
Conditions associated with CASR
Gene function
What if the gene works
Keeping calcium in range matters for muscle movement, nerve signals, and many routine body functions. In your body, the CASR gene supports processes that help certain cells sense calcium levels, especially in the parathyroid glands and kidneys. This is a key part of how your body keeps blood calcium levels in balance from moment to moment.
The CASR gene helps certain cells detect how much calcium is present outside the cell, including in the blood. That first sensing step tells the body when calcium balance needs a small adjustment.
In the parathyroid glands, the CASR gene helps guide release of parathyroid hormone, a hormone that helps manage blood calcium. This keeps hormone signaling matched to the body's current calcium level.
In the kidneys, the CASR gene helps fine tune how much calcium is kept in the body and how much leaves in urine. This supports steady calcium handling across the day.
By coordinating calcium sensing in key organs, the CASR gene helps maintain a healthy mineral balance. This supports normal nerve signaling, muscle function, and other everyday body processes that depend on calcium.
What is a variant?
A genetic variant is a minor change in a gene’s DNA sequence. These changes are common and help shape normal human diversity, including differences in appearance, metabolism, and how the body reacts to environmental influences. Many variants do not have any noticeable effect and are simply part of natural genetic variation. In some situations, though, a variant can change how a gene works more significantly and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the CASR gene can make the receptor less sensitive or more sensitive to calcium, or keep it from reaching the cell surface in the right shape. This is how CASR gene variants affect calcium sensing: cells misread calcium levels and send the wrong follow-up messages. Milder variants may partly reduce or increase receptor activity, while more severe variants can cause a larger functional change and may be linked to earlier or more marked calcium-balance problems.
How variants are linked to conditions
Variants in the CASR gene are best known for causing inherited conditions linked to abnormal calcium levels in the blood. Pathogenic changes can cause familial hypocalciuric hypercalcemia type 1 or autosomal dominant hypocalcemia type 1, and more disruptive variants in both copies of the CASR gene can lead to neonatal severe hyperparathyroidism. In broader studies, some CASR variants have also been associated with small differences in calcium levels and kidney stone risk.
A variant is not necessarily a diagnosis
Genetic variants are a usual part of human biology and are widely found in the general population. Most do not have a direct effect on health and simply contribute to natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible link rather than a definite diagnosis, especially when several genes and environmental factors are involved. In some situations, though, a single well-characterized variant in a specific gene can be enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For CASR-related conditions, risk is usually shaped mainly by the specific gene change you inherit, so family history matters most. Some medicines, including lithium and certain water pills, can raise calcium levels and may make a CASR-related high-calcium condition more noticeable or harder to manage.
Inheritance of CASR variants
CASR-related conditions can be inherited in different ways, so how CASR gene variants are inherited depends on the specific condition and variant. Many CASR gene changes linked to familial hypocalciuric hypercalcemia or autosomal dominant hypocalcemia follow an autosomal dominant pattern, which means a parent with the variant can pass it to each child with a 50% chance. Some more severe CASR-related conditions, including neonatal severe hyperparathyroidism, usually follow an autosomal recessive pattern, meaning a child inherits one altered copy from each parent. The CASR gene is on chromosome 3, so these patterns affect sons and daughters equally.
What does my CASR result mean for my family?
A CASR result can matter for close relatives, but what it means depends on the specific change and the condition linked to it. Some CASR changes run in families in a dominant pattern, so parents, brothers, sisters, and children may also carry the same change. Other CASR-related conditions are seen when both copies of the gene are changed, which can mean relatives may be healthy carriers.
Genetic information
Genetic testing
How you find out about variants
To understand how CASR genetic testing works, a lab analyzes DNA from a blood or saliva sample, often as part of a calcium disorder panel or broader sequencing test. The lab reads the gene's code, compares it with a reference sequence, and reports whether a variant is found and how it is classified.
When should I consider getting a genetic test?
Consider testing for changes in the CASR gene if you or close relatives have lifelong high calcium levels, repeated low calcium episodes, or parathyroid problems that run in the family. A CASR test can help show whether the pattern fits an inherited condition affecting calcium balance and may help avoid unnecessary treatment.
A genetic result is only one part of your health story
Genetic test results can provide valuable insight, but what they show depends on the condition and the kind of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, influence how the body functions. For some conditions, especially those affected by many genes, genetic information provides context rather than certainty and is most useful when viewed alongside other parts of care. In other situations, a genetic result can give a clear answer. In areas such as medication response, genetic results can also help make individual experiences easier to understand.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how your body handles certain medicines, which helps explain why the same treatment may work well for one person but less well for another. These inherited differences can change how a drug is absorbed, broken down, or acts in the body, and that can influence how much benefit you get or how sensitive you are to side effects. This kind of variation is common and is one of several reasons medication response differs from person to person.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape the way people respond to medications. It studies links between genes and drugs to help explain why the same treatment may affect one person differently than another. With many medicines, genes can influence both how the body handles a drug and how strong its effects are. This information can support treatment choices that are more informed and more personalized. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the CASR gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding drug treatment, so questions about side effects, new symptoms, or medication changes are best discussed with your doctor. Some research has explored whether CASR changes affect response to medicines that act on calcium balance, including cinacalcet, but this is not yet part of routine care.
History
Researchers identified the CASR gene in the early 1990s while studying how the body senses calcium, a discovery that helped explain several inherited calcium balance conditions. Initially understood only through visible traits, later recognized as tied to a specific gene, these family patterns had puzzled doctors for years. The finding of the calcium sensing receptor was an important step in hormone and kidney research because it connected clinical observations with a clear genetic cause. Building on this early work, scientists linked variants in the CASR gene to conditions such as familial hypocalciuric hypercalcemia and some forms of low blood calcium. Over time, descriptions became more precise. Today, CASR remains a well known example of how gene discovery can clarify a long standing medical mystery.