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Calcium-Sensing Receptor (CASR) Gene Sequencing Analysis
- CASR gene
CASR encodes the calcium sensing receptor (CaSR) which, when activated (1) inhibits secretion of parathyroid hormone (PTH), (2) stimulates calcitonin release from the thyroid, and (3) stimulates urinary calcium excretion. CASR mutations can result in calcium dysregulation:
• Heterozygous inactivating mutations cause familial hypocalciuric hypercalcemia (FHH)
• Homozygous inactivating mutations cause neonatal severe hyperparathyroidism (NSHPT)
• Heterozygous activating mutations cause autosomal dominant hypocalcemia (ADH) or Bartter syndrome type V
Detection rates range from 18-70% for hypercalcemia and approximately 40% for hypocalcemia, as there are additional genes that affect calcium regulation.
Identification of CASR mutations can be used to:
• Determine the cause of hypercalcemia in patients considering parathyroid surgery (CASR mutations are not usually associated with PTH-producing tumors)
• Confirm the diagnosis of NSHPT, leading to urgent parathyroidectomy
• Identify individuals with ADH who are at risk for developing kidney stones with vitamin D supplements
• Influence treatment options with calcimimetic or calcilytic therapies
Mutations that are not in exons 2 through 7 are not analyzed and will not be detected. Polymorphisms at PCR primer target sites may lead to false-negative results. This method will not detect changes in CASR gene copy number or in other genes that affect calcium homeostasis.
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).
Polymerase chain reaction (PCR) and Sanger sequencing of targeted CASR exons, gel electrophoresis
Lavender-top (EDTA) tube or yellow-top (ACD) tube
Causes for Rejection
Serum or plasma specimens; frozen samples; hemolyzed samples
Testing is performed at Esoterix Endocrinology Laboratory.
Test orders must include an attestation that the provider has the patient's informed consent for genetic testing (see Related Documents). In the case of family tests (ie, known mutations), please submit the result report of the first patient tested in the family (the index case), if not performed at a LabCorp facility. Other family members are subsequently tested for the specific mutation found in the first patient tested.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|504513||CASR Gene Sequencing||504514||CASR Gene Sequencing||82534-9|
|504513||CASR Gene Sequencing||504516||Result||19146-0|
|504513||CASR Gene Sequencing||504517||Interpretation||50397-9|
|504513||CASR Gene Sequencing||504518||Comments||8251-1|
|504513||CASR Gene Sequencing||504520||References||75608-0|