title: A novel CDC73 gene mutation in an Italian family with hyperparathyroidism-jaw tumour (HPT-JT) syndrome.
abstract: OBJECTIVE
  The CDC73 gene, encoding parafibromin, has been identified as a tumour suppressor gene both in hyperparathyroidism-jaw tumour (HPT-JT) syndrome and in sporadic parathyroid carcinoma. While the vast majority of CDC73 mutations affect the N-terminus or the central core of the encoded protein, as yet few mutations have been reported affecting the C-terminus. Here, we report a case (Caucasian female, 28 years) with an invasive ossifying fibroma of the left mandible and hyperparathyroidism (sCa = 16 mg/dl, PTH = 660 pg/mL) due to a parathyroid lesion of 20 mm, hystologically diagnosed as carcinoma.
  
  
  METHODS
  The whole CDC73 gene was screened for the presence of mutations by Sanger sequencing. Immunohistochemistry, in vitro functional assays, Western blotting, MTT assays and in-silico modelling were performed to assess the effect of the detected mutation.
  
  
  RESULTS
  Sequence analysis of the CDC73 gene in the proband revealed the presence of a novel deletion affecting the C-terminus of the encoded protein (c.1379delT/p.L460Lfs*18). Clinical and genetic analyses of the available relatives led to the identification of three additional carriers, one of whom was also affected by a parathyroid lesion. Immunohistochemistry, Western blotting, MTT and in-silico modelling assays revealed that the deletion leads to down-regulation of the mutated protein, most likely through a proteasome-mediated pathway. We also found that the deletion may cause a conformational change in the C-terminus of the protein, possibly affecting its interaction with partner proteins. Finally, we found that the mutant protein enhances cellular growth.
  
  
  CONCLUSIONS
  We report a novel mutation in the CDC73 gene that may underlie HPT-JT syndrome. This mutation appears to affect the C-terminal moiety of the encoded protein, which is thought to interact with other protein partners. The identification of these partners may be instrumental for our understanding of the CDC73-associated phenotype.
authors.affiliation: Thyroid and Parathyroid Surgery Unit, Istituto Nazionale Tumori Fondazione "G. Pascale", via Mariano Semmola, Naples, 80131, Italy.
authors.forename: M G
authors.initials: MG
authors.lastname: Chiofalo
authors.forename: A
authors.initials: A
authors.lastname: Sparaneo
authors.forename: M
authors.initials: M
authors.lastname: Chetta
authors.forename: R
authors.initials: R
authors.lastname: Franco
authors.forename: F
authors.initials: F
authors.lastname: Baorda
authors.forename: L
authors.initials: L
authors.lastname: Cinque
authors.forename: M
authors.initials: M
authors.lastname: Granatiero
authors.forename: L
authors.initials: L
authors.lastname: D'Agruma
authors.forename: L
authors.initials: L
authors.lastname: Pezzullo
authors.forename: A
authors.initials: A
authors.lastname: Scillitani
authors.forename: V
authors.initials: V
authors.lastname: Guarnieri
mesh_terms: D000236:Adenoma / Q000235:genetics*; D000328:Adult; D002460:Cell Line; D005260:Female; D005350:Fibroma / Q000235:genetics*; D018095:Germ-Line Mutation / Q000235:genetics; D006801:Humans; D006961:Hyperparathyroidism / Q000235:genetics*; D007558:Italy; D007573:Jaw Neoplasms / Q000235:genetics*; D008297:Male; D009154:Mutation / Q000235:genetics*; D017433:Protein Structure, Secondary; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: C454900:CDC73 protein, human; D025521:Tumor Suppressor Proteins
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