Hyperparathyroidism-jaw tumor syndrome

Hyperparathyroidism-jaw tumor syndrome is an extremely rare condition where a gene mutation results in hyperparathyroidism in association with both benign and malignant tumors, most notably, tumors in the mandible or maxilla .

Epidemiology

Approximately 200 cases have been reported in the medical literature.

Clinical presentation

Onset most commonly is in early adulthood or late adolescence, with the condition characterized by hyperparathyroidism and tumors:

• hyperparathyroidism:
  • primary hyperparathyroidism occurs in up to 95% of cases
  • it is often associated with a single parathyroid adenoma or parathyroid carcinoma 
  • patients will often present with features of resultant hypercalcemia
• tumors:
  • 30-40% of individuals develop ossifying fibromas of the mandible or maxilla, presenting with facial disfigurement  
  • 20% of affected individuals present with kidney lesions including cysts (most common), Wilms tumor, and renal hamartomas 
  • female individuals with this syndrome usually have benign or malignant uterine tumors

Pathology

Genetics 

Hyperparathyroidism-jaw tumor syndrome is usually caused by mutations in the CDC73 gene (also known as the HRPT2 tumor suppressor gene) . This gene is responsible for the creation of parafibromin which is a protein responsible for various gene transcriptions throughout the body as well as regulating cell growth and proliferation. Mutations often cause a parafibromin protein that is too short and non-functional . This anomaly is inherited in an autosomal dominant pattern .