Potential utility of cinacalcet as a treatment for CDC73-related primary hyperparathyroidism: a case report.

We report a Japanese pedigree with familial primary hyperparathyroidism due to a CDC73 mutation. To our knowledge, this is the first report of cinacalcet as a treatment for CDC73-related primary hyperparathyroidism. The proband had severe psychomotor retardation and received laryngotracheal separation surgery. At 19 yr of age, he developed acute pancreatitis. Hypercalcemia (12.2-13.8 mg/dL), elevated levels of intact PTH (86-160 pg/mL), and a tumor detected upon neck ultrasonography led to the diagnosis of primary hyperparathyroidism. Family history and biochemical examinations revealed that three family members (the proband's mother, elder brother, and maternal grandfather) had primary hyperparathyroidism. We identified a novel heterozygous mutation, c.240delT, p.Glu81Lysfs*28, in the CDC73 gene in three affected family members, excluding the proband's elder brother who refused genetic testing. Parathyroidectomy for the proband was considered as high-risk, because the tumor was located close to the tracheostomy orifice. After receiving approval from the institutional review board and obtaining the consent, we initiated cinacalcet treatment. At 22 yr of age, treatment with 100 mg of cinacalcet maintained serum calcium levels below 11.0 mg/dL with no apparent side effects. Our report presents the potential efficacy of cinacalcet as a treatment for CDC73-related primary hyperparathyroidism, in particularly inoperative cases.