Hyperparathyroidism-jaw tumor (HPT-JT)-syndrome: three case reports

Primary hyperparathyroidism (pHPT) is the most common disease of the parathyroid glands. Only about 1% of all patients with pHPT have familial isolated hyperparathyroidism (FIHP). Syndromes that go along with pHPT are: MEN 1, MEN 2, familial hypocalcuric hypercalcemia (FHH) and the hyperparathyroidism-jaw tumor (HPT-JT)-syndrome. Recently, the gene responsible for the HPT-JT-syndrome, HRPT2, localized on Chromosom 1q25, was identified. We report on three patients with HPT-JT-syndrome who underwent surgery in our clinic.

A 20 year-old male underwent subtotal parathyroidectomy due to pHPT. Orofacial dysplacia was also present and the clinical diagnosis HPT-JT-syndrome was made. All removed parathyroid glands showed hyperplasia, no signs of malignancy were found. PTH dropped from 124,7 pg/ml to 31,3 pg/ml postoperatively (normal range 10–72 pg/ml). His father, who also had orofacial dysplacia, underwent total parathyroidectomy and autotransplanation of two subtotal parathyroid glands. Three parathyroid glands showed abnormal histology, malignany was not suspected. PTH dropped from 396 pg/ml to 1 pg/ml postoperatively. Mutation analysis of both relatives identified the mutation c.76delA in HRPT2. A not-related 35 year-old female with orofacial dysplacia underwent laryngectomy due to recurrence of parathyroid carcinoma. Mutation analysis revealed the mutation c.76delA in HRPT2.

The identification of mutations in HRPT2 is not only important for the patients but also their relatives, in particular their offsprings. The risk to inherit the gene is 50% and patients with HPT-JT-syndrome do have a risk of developing parathyroid cancer of up to 15%. Early diagnosis is desirable to avoid extensive operations as seen in the female.