Familial hyperparathyroidism: surgical outcome after 30 years of follow-up in three families with germline HRPT2 mutations

Abstract

Familial forms of hyperparathyroidism are responsible for approximately 10% of the cases of primary hyperparathyroidism, and their management is different from the sporadic forms. Our objective was to study the gene sequence and expression of HRPT2 and clinical outcome regarding recurrence or persistence rates in three Brazilian kindreds with familial hyperparathyroidism after up to 30 years of follow-up. Clinical and biochemical data, direct sequencing of germline DNA of the HRPT2 gene, and analysis of parafibromin expression (HRPT2 gene product) using RT-PCR and immunohistochemistry of resected parathyroid neoplasms were performed. Affected members of kindred A were found to carry a novel, germline, nonsense mutation in exon 1 (c.96G>A; W32X) of HRPT2. Six of seven patients who have undergone less than total parathyroidectomy recurred after up to 30 years of follow-up. An unrelated affected patient from kindred B had a germline mutation in exon 7 (c.686delGAGT), and the disease recurred with several pulmonary metastases after 5 years follow-up. The affected member of kindred C also had a previously described mutation in exon 7 (c.679delAG) and the disease recurred after 10 years of follow-up. All parathyroid neoplasms from these families had diffuse loss of expression by immunohistochemistry. An unacceptable recurrence/persistence rate (80%) associated with increasingly difficult re-operations and risk of parathyroid carcinoma in the setting of germline mutations of HRPT2 gene with familial hyperparathyroidism suggest that a more aggressive operative approach should be undertaken in these patients. Parafibromin immunohistochemistry may serve as a cost-effective screen for HRPT2-related aggressive parathyroid disease.