Endocrine Abstracts

Hyperparathyroidism jaw tumour syndrome (HPT-JT) is an autosomal dominant disease with variable penetrance. Onset is typically in late adolescence or early adulthood. Primary hyperparathyroidism is typically caused by a single parathyroid adenoma but parathyroid carcinoma occurs in 10–15%. Ossifying fibroma of the mandible or maxilla occurs in 30–40%, and may be locally aggressive. 15% of patients have renal manifestations which include polycystic kidney disease, Wilms tumour and renal cell carcinoma. In women there is an increased risk of uterine tumours. The gene causing HPT-JT, HRPT2, is located on chromosome 1q31.2a, coding for parafibromin (tumour suppressor gene) found in 50–75%.

We recently identified a patient with HPT-JT which led to detection of a kindred with the CDC73 pathogenic variant. A 54-year-old male presented to the maxillofacial services for surgical removal of a jaw tumour. Histology confirmed an ossifying fibroma of the maxilla. During his admission he was noted to have hypercalcaemia (Ca⁺⁺3.2 mmol/l, PTH 110 pmol/l).

On review of previous history, he described poor dentition since the age of 20, and he reported that his sister had died at the age of 35 from metastatic parathyroid carcinoma. Diagnosis of primary hyperparathyroidism was established and he underwent parathyroid surgery with normalisation of Ca⁺⁺ and PTH. Histology was consistent with parathyroid adenoma.

His genetic analysis detected a mutation in the CDC73 gene (Exon 7 c.664 C to T leading to protein PArg222Ter). Family members were screened, which confirmed CDC73 mutation in one daughter and one son, and 1 son was mutation negative.