2. Heterozygote inherited inactivating mutations in Calcium Sensing Receptor (CaSR)-gene leads to familiar hypocalciuric hypercalcemia (FHH), specified by mildly elevated plasma Ca and parathyroid hormone concentrations, whereas urine Ca excretion is inadequately low. However, in addition to the parathyroid gland CaSR is expressed in various tissues including the endocrine pancreas and the heart. So far it is unknown whether the endocrine function of the pancreas or myocardial morphology and/or function is altered in patients with FHH.