title: GNAS Mutations in Fibrous Dysplasia: A Comparative Study of Standard Sequencing and Locked Nucleic Acid PCR Sequencing on Decalcified and Nondecalcified Formalin-fixed Paraffin-embedded Tissues.
abstract: It is well known that fibrous dysplasia (FD) is characterized by the presence of activating mutations involving G-nucleotide binding protein-α subunit (GNAS) involving codon R201 and rarely codon 227 with a mutation frequency between 45% and 93%. Herein, we investigate the sensitivity of detection of GNAS mutations in exons 8 and 9 using a standard and a highly sensitive locked nucleic acid polymerase chain reaction (LNA-PCR) sequencing in 52 cases of FD. In view of the recent report of GNAS mutations in a small number of low-grade osteosarcomas, we also tested in addition 12 cases of low-grade osteosarcomas. GNAS exon 8 mutations p.R201H (31%), p.R201C (15%), and p.R201S (2%) were identified in 50% of FD cases. LNA-PCR sequencing identified only 1 positive case within the mutation negative cases tested by standard PCR and Sanger sequencing. No mutations were identified in any of the low-grade osteosarcomas by standard and LNA-PCR sequencing. There was no association between age, site, size, specimen type, and mutational status. No exon 9 or codon 227 mutations were identified in any of tested cases. There was a significant difference in the sensitivity of the assay between decalcified and nondecalcified FDs (31% vs. 70%, P=0.002). LNA-PCR has no added value in enhancing detection sensitivity for GNAS mutations in FD. In addition to decalcification, innate somatic mosaicism contributes to the decreased sensitivity in mutation detection.
authors.affiliation: Departments of *Pathology †Orthopedic Surgery, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: George
authors.initials: G
authors.lastname: Jour
authors.forename: Alifya
authors.initials: A
authors.lastname: Oultache
authors.forename: Justyna
authors.initials: J
authors.lastname: Sadowska
authors.forename: Talia
authors.initials: T
authors.lastname: Mitchell
authors.forename: John
authors.initials: J
authors.lastname: Healey
authors.forename: Khedoudja
authors.initials: K
authors.lastname: Nafa
authors.forename: Meera
authors.initials: M
authors.lastname: Hameed
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000235:genetics* / Q000473:pathology; D002114:Calcinosis; D002648:Child; D002675:Child, Preschool; D002864:Chromogranins / Q000235:genetics*; D005260:Female; D005557:Formaldehyde; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009841:Oligonucleotides / Q000235:genetics*; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction; D017421:Sequence Analysis / Q000379:methods; D055815:Young Adult
chemical_list: D002864:Chromogranins; D009841:Oligonucleotides; C477371:locked nucleic acid; D005557:Formaldehyde; C406732:GNAS protein, human; D019205:GTP-Binding Protein alpha Subunits, Gs