Endocrine Abstracts

Inactivating germline mutations in the HRPT2 tumor suppressor gene are the cause of the hyperparathyroidism-jaw tumor syndrome (HPT-JT). The most common feature of HPT-JT is primary hyperparathyroidism, followed by ossifying fibromas of the maxilla and mandible, renal cysts and solid tumors. As recently recognized, mutations of this gene also play a central role in the molecular pathogenesis of parathyroid carcinoma.

A 19-year-old woman presented with a giant cell granuloma of the right mandible which was surgically removed. One year later, she presented with a recurrence of the giant cell granuloma. Serum calcium (3.65 mmol/l) and PTH (398 ng/l) were elevated and the patient was diagnosed for primary hyperparathyroidism. Surgical exploration revealed a parathyroid adenoma on the left side. Postoperatively serum calcium and PTH were within the normal range for the last 10 years.

Mutation analysis revealed the heterozygous mutation c.1423_1433delCT in exon 16 of the HRPT2 gene. This mutation has not been described yet and leads to a shift in the reading frame with a premature stop-codon.

The identification of the c.1423_1433delCT mutation is not only important for the patient herself, but it is also important for other family members who could benefit from the identification as mutation carriers. The patients sister (33 years old) has an encapsulated tumor of the right hip since the age of 12, but has not yet been diagnosed for the HPT-JT syndrome. Early diagnosis can be used for the detection and removal of malignant parathyroid and other associated tumors.