title: 20 novel point mutations and one large deletion in EXT1 and EXT2 genes: report of diagnostic screening in a large Italian cohort of patients affected by hereditary multiple exostosis.
abstract: BACKGROUND
  Hereditary multiple exostosis represents the most frequent bone tumor disease in humans. It consists of cartilage deformities affecting the juxta-ephyseal region of long bones. Usually benign, exostosis could degenerate in malignant chondrosarcoma form in less than 5% of the cases. Being caused by mutations in the predicted tumor suppressor genes, EXT1 (chr 8q23-q24) and EXT2 (chr 11p11-p12) genes, HMEs are usually inherited with an autosomal dominant pattern, although "de novo" cases are not infrequent.
  
  
  OBJECTIVE
  Here we present our genetic diagnostic report on the largest Southern Italy cohort of HME patients consisting of 90 subjects recruited over the last 5years.
  
  
  RESULTS
  Molecular screening performed by direct sequencing of both EXT1 and EXT2 genes, by MLPA and Array CGH analyses led to the identification of 66 mutations (56 different occurrences) and one large EXT2 deletion out of 90 patients (74.4%). The total of 21 mutations (20 different occurrences, 33.3%) and the EXT2 gene deletion were novel. In agreement with literature data, EXT1 gene mutations were scattered along all the protein sequence, while EXT2 lesions fell in the first part of the protein. Conservation, damaging prediction and 3-D modeling, in-silico, analyses, performed on three novel missense variants, confirmed that at least in two cases the novel aminoacidic changes could alter the structure stability causing a strong protein misfolding.
  
  
  CONCLUSIONS
  Here we present 20 novel EXT1/EXT2 mutations and one large EXT2 deletion identified in the largest Southern Italy cohort of patients affected by hereditary multiple exostosis.
authors.affiliation: Medical Genetics, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy. ciavarellamichele@hotmail.it
authors.forename: Michele
authors.initials: M
authors.lastname: Ciavarella
authors.forename: Michelina
authors.initials: M
authors.lastname: Coco
authors.forename: Filomena
authors.initials: F
authors.lastname: Baorda
authors.forename: Pietro
authors.initials: P
authors.lastname: Stanziale
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Chetta
authors.forename: Luigi
authors.initials: L
authors.lastname: Bisceglia
authors.forename: Pietro
authors.initials: P
authors.lastname: Palumbo
authors.forename: Mario
authors.initials: M
authors.lastname: Bengala
authors.forename: Paola
authors.initials: P
authors.lastname: Raiteri
authors.forename: Margherita
authors.initials: M
authors.lastname: Silengo
authors.forename: Camilla
authors.initials: C
authors.lastname: Caldarini
authors.forename: Renato
authors.initials: R
authors.lastname: Facchini
authors.forename: Roberto
authors.initials: R
authors.lastname: Lala
authors.forename: Maria Luigia
authors.initials: ML
authors.lastname: Cavaliere
authors.forename: Davide
authors.initials: D
authors.lastname: De Brasi
authors.forename: Barbara
authors.initials: B
authors.lastname: Pasini
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Zelante
authors.forename: Vito
authors.initials: V
authors.lastname: Guarnieri
authors.forename: Leonardo
authors.initials: L
authors.lastname: D'Agruma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D055028:Comparative Genomic Hybridization; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D005097:Exostoses, Multiple Hereditary / Q000235:genetics*; D005260:Female; D056726:Genetic Association Studies; D006801:Humans; D007223:Infant; D007558:Italy; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics*; D010375:Pedigree; D017354:Point Mutation; D020641:Polymorphism, Single Nucleotide; D020033:Protein Isoforms / Q000235:genetics; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D055815:Young Adult; D000099065:Exostosin 2; D000099058:Exostosin 1
chemical_list: D020033:Protein Isoforms; D017351:N-Acetylglucosaminyltransferases; D000099058:Exostosin 1; D000099065:Exostosin 2