Most cases of<unk>  are associated with loss of function mutations in the calcium-sensing receptor (CaSR) gene, expressed in parathyroid and kidney tissue. These mutations decrease the receptor's sensitivity to calcium, resulting in reduced receptor stimulation at normal serum calcium levels. As a result, inhibition of parathyroid hormone release does not occur until higher serum calcium levels are attained, creating a new equilibrium. This is the opposite of what happens with the CaSR sensitizer, cinacalcet. Functionally, parathyroid hormone (PTH) increases calcium resorption from the bone and increases phosphate excretion from the kidney which increases serum calcium and decreases serum phosphate. Individuals with<unk> , however, typically have normal PTH levels, as normal calcium homeostasis is maintained, albeit at a higher equilibrium set point. As a consequence, these individuals are not at increased risk of the complications of hyperparathyroidism. Another form has been associated with chromosome 3q. Functions of the calcium-sensing receptor * Parathyroid gland: mediates negative feedback mechanisms relating to PTH secretion. In normal individuals, PTH secretion decreases with increasing blood calcium levels. Loss of function abnormalities in the CaSR here cause<unk> . * Kidneys: mediates negative feedback mechanisms relating to calcium reabsorption from the tubular system. In normal individuals, reabsorption of calcium and other electrolytes decreases with increasing blood calcium level. Loss of function abnormalities in the CaSR here contribute to both<unk>  and<unk> .
Familial hypocalciuric hypercalcemia
Primary hyperparathyroidism
Secondary hyperparathyroidism
Tertiary hyperparathyroidism
Normophosphatemic familial tumoral calcinosis
Pseudohypoparathyroidism
Pseudopseudohypoparathyroidism
Hyperphosphatasia with mental retardation syndrome