title: Somatic mutation and germline sequence abnormalities in CDKN1B, encoding p27Kip1, in sporadic parathyroid adenomas.
abstract: BACKGROUND
  Typical nonfamilial (sporadic) parathyroid adenomas are common endocrine tumors for which no predisposing germline DNA variants and only a few clonally altered genes that drive parathyroid tumorigenesis have been identified. CDKN1B, encoding cyclin-dependent kinase inhibitor p27(kip1), has recently been implicated in a multiple endocrine tumor phenotype in rats and, rarely, in a human familial MEN1 (multiple endocrine neoplasia type 1)-like disorder.
  
  
  OBJECTIVE
  We sought to determine whether mutation of CDKN1B might contribute to the development of common sporadic parathyroid adenomas.
  
  
  METHODS
  We sequenced the CDKN1B gene in 86 parathyroid adenomas from patients with typical, sporadic presentations of primary hyperparathyroidism. Identified alterations were categorized as somatic or germline, and their functional consequences were examined.
  
  
  RESULTS
  CDKN1B sequence abnormalities were identified in four parathyroid adenomas. Acquired biallelic alteration of CDKN1B, resulting from somatic mutation plus loss of heterozygosity, was detected in one tumor. Germline origin was documented in two cases despite nonfamilial presentations. None of the observed alterations were found in 240 CDKN1B alleles from normal individuals, nor among more than 2,000 previously reported alleles. Most identified variants reduced p27(kip1) protein levels or altered in vitro stability.
  
  
  CONCLUSIONS
  In typical, sporadic parathyroid adenomas, CDKN1B mutation can be somatic and clonal, indicative of a directly conferred selective advantage in parathyroid tumorigenesis. Additionally, the identification of germline CDKN1B variants in patients with sporadic presentations provides evidence for CDKN1B as a susceptibility gene in the development of typical parathyroid adenomas.
authors.affiliation: Center for Molecular Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030-3101, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Costa-Guda
authors.forename: Ilaria
authors.initials: I
authors.lastname: Marinoni
authors.forename: Sara
authors.initials: S
authors.lastname: Molatore
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Pellegata
authors.forename: Andrew
authors.initials: A
authors.lastname: Arnold
mesh_terms: D000236:Adenoma / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D020022:Genetic Predisposition to Disease; D018095:Germ-Line Mutation / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000502:physiology; D016366:Open Reading Frames / Q000235:genetics; D010282:Parathyroid Neoplasms / Q000235:genetics*
chemical_list: C436291:CDKN1B protein, human; D050760:Cyclin-Dependent Kinase Inhibitor p27