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Familial Hypocalciuric Hypercalcemia (HHC1/FHH)
Neonatal Severe Primary Hyperparathyroidism (NSHPT)
Hypocalcemia, Autosomal Dominant (ADH)
Hypoparathyroidism, Familial Isolated (FIH)
CASR (Calcium sensing receptor)
Individuals with
HHC1/FHH
are generally asymptomatic throughout life and do not require treatment.
Affected individuals have mild or moderate elevations of calcium in serum and relative hypocalciuria, and inappropriately normal serum parathyroid levels. Some patients experience pancreatitis, gall stones, renal stones, or chondrocalcinosis. Affected individuals may also have fatigue, weakness, mental disturbance, and polydipsia/polyuria, albeit of lesser severity than is typically observed in primary hyper-parathyroidism.
AD
has as its most common presenting symptom neonatal or childhood seizures, which are usually secondary to infection and fever. Mild hypocalcemia is present, usually with no overt symptoms. There is a tendency, however, towards hyperphosphatemia. Serum intact parathyroid levels are usually normal. Clinically there is an increased risk for renal complications, including nephrocalcinosis, renal stones, and impaired renal function.
FIH
is characterized by hypocalcemia and hyperphosphatemia due to inadequate secretion of parathyroid hormone (PTH). Symptoms are seizures, tetany and muscle cramps.
NSHPT
is a rare life-threatening disorder characterized by very high serum calcium concentrations, skeletal demineralization, and multi-glandular parathyroid hyperplasia. Infants present with lethargy, hypotonia, failure to thrive, bony undermineralization, multiple fractures, and severe skeletal deformities, including thoracic narrowing that can lead to respiratory disease. Symptoms occur before the age of 6 months and, if left untreated, can lead to florid rickets, devastating neurodevelopmental disorders, and often fatality. Usually parathyroidectomy is necessary within the first few weeks of life to prevent death.
We offer mutation analysis of the CASR gene. Using genomic DNA obtained from buccal (cheek) swabs or blood (1-5cc in EDTA), all coding exons of the CASR gene are screened by bi-directional sequence analysis. Two-thirds of HHC1/FHH pedigrees show inactivating mutations in the CASR gene. For ADH, one small study found activating CASR gene mutations in 42% of patients with isolated hypoparathyroidism. The majority of mutations causing HHC1/FHH are missense changes, and other mutation types have also been reported. De novo mutation is common, particularly in HHC1/FHH and NSHPT. Prenatal diagnosis is available once the mutation in a family has been defined.
Information Sheet, including prices and CPT codes
Consent Document
Genetic Test Sample Submission Form (Test Requisition Form) including Payment Options
Hypoparathryoidism, Hypoparathyroid, Parathyroid, Hypocalciuria, Hypocalciuric, Hypocalcuria, Hypocalcuric, CASR, Calcium
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