title: Identification of the first germline HRPT2 whole-gene deletion in a patient with primary hyperparathyroidism.
abstract: OBJECTIVE
  Germline mutations in the HRPT2 gene are associated with the hereditary hyperparathyroidism-jaw tumour syndrome (HPT-JT) and a subset of familial isolated hyperparathyroidism (FIHP). Somatic HRPT2 mutations are detected in sporadic parathyroid carcinomas and less frequently in cystic adenomas. The purpose of this study was to investigate the underlying HRPT2 defect in a young patient with symptomatic hyperparathyroidism due to an apparently sporadic parathyroid adenoma with cystic features.
  
  
  METHODS
  HRPT2 mutations in the patient's genomic and parathyroid tumour DNA were screened by PCR-based sequencing. Tumour loss of heterozygosity (LOH) at the HRPT2 locus was assessed with microsatellite markers. A large germline HRPT2 deletion was investigated by real-time quantitative PCR analysis (qPCR). Genomic DNA losses were also appraised by chromosomal comparative genomic hybridization (cCGH).
  
  
  RESULTS
  No germline HRPT2 point mutation was detected by direct sequencing. A novel hemizygous HRPT2 somatic mutation (c.32delA) was identified in the tumour. Apparent constitutional homozygosity for HRPT2 flanking microsatellite markers, and absence of LOH at a distal marker, suggested a large germline deletion. Gene dose mapping by qPCR unveiled a de novo deletion of the whole HRPT2 gene and adjacent loci (<9·3 Mb in size). cCGH confirmed germline DNA loss involving the HRPT2 locus.
  
  
  CONCLUSIONS
  We report the first large germline deletion of the HRPT2 gene, which was not detectable by conventional PCR-based sequencing methods. This finding emphasizes that qPCR should be implemented in HRPT2 molecular analysis, which may improve genetic assessment and clinical management of patients with FIHP and HPT-JT.
authors.affiliation: Centro de Investigação de Patobiologia Molecular, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisboa, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Domingues
authors.forename: Rute Alexandra
authors.initials: RA
authors.lastname: Tomaz
authors.forename: Carmo
authors.initials: C
authors.lastname: Martins
authors.forename: Carla
authors.initials: C
authors.lastname: Nunes
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Bugalho
authors.forename: Branca Maria
authors.initials: BM
authors.lastname: Cavaco
mesh_terms: D000328:Adult; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D017353:Gene Deletion; D018095:Germ-Line Mutation; D006801:Humans; D006961:Hyperparathyroidism / Q000235:genetics*; D008297:Male; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: C454900:CDC73 protein, human; D025521:Tumor Suppressor Proteins; D004247:DNA