INS and familial hypocalciuric hypercalcemia: For example, one patient-based association study has reported a common coding region CaSR gene variant to be an independent determinant of plasma glucose concentrations (12), whereas another study of patients with familial hypocalciuric hypercalcemia (FHH), which is caused by germline loss-of-function CaSR mutations, did not reveal any alterations in glucose tolerance or insulin secretion (13).