title: Novel EXT1 and EXT2 mutations identified by DHPLC in Italian patients with multiple osteochondromas.
abstract: We describe the results of an optimised DHPLC-based mutation screening of the EXT1 and EXT2 genes in Italian patients affected by multiple osteochondromas [MO; also referred to as hereditary multiple exostoses (HME) in the literature], using a multistep approach. We first analysed 36 unrelated probands for EXT1 mutations by DHPLC analysis and subsequent direct sequencing of all samples with abnormal elution profile. Negative cases were then screened for EXT2 mutations using the same approach. In patients who tested normal at DHPLC screening, all EXT1 and EXT2 exons and splice-site junctions were directly sequenced. In 7 informative families, we also performed a pre-screening linkage analysis to selectively focus the DHPLC testing on the EXT1 or EXT2 gene. We detected 31 MO-related mutations, of which 23 (74%) were novel. Seven polymorphisms were also found. Twenty-four mutations (77%) were found in EXT1 and 7 (23%) in EXT2. No disease-causing mutations were detected in five of 36 patients, with a mutation frequency of 86%. According with previous studies, most mutations (90%) are loss of function. Neither false positive nor false negative results were obtained. This multistep method can be considered a fast and reliable diagnostic strategy for the detection of EXT1/2 mutations, with excellent sensitivity and specificity.
authors.affiliation: Modulo di Familiarità e Genetica, Lab. Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Pedrini
authors.forename: Alessandro
authors.initials: A
authors.lastname: De Luca
authors.forename: Enza Maria
authors.initials: EM
authors.lastname: Valente
authors.forename: Veronica
authors.initials: V
authors.lastname: Maini
authors.forename: Silvia
authors.initials: S
authors.lastname: Capponcelli
authors.forename: Marina
authors.initials: M
authors.lastname: Mordenti
authors.forename: Rita
authors.initials: R
authors.lastname: Mingarelli
authors.forename: Luca
authors.initials: L
authors.lastname: Sangiorgi
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallapiccola
mesh_terms: D017398:Alternative Splicing; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004252:DNA Mutational Analysis / Q000379:methods*; D017931:DNA Primers / Q000737:chemistry; D005097:Exostoses, Multiple Hereditary / Q000235:genetics*; D005189:False Positive Reactions; D008040:Genetic Linkage; D006801:Humans; D007558:Italy; D009154:Mutation; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics*; D011110:Polymorphism, Genetic; D012680:Sensitivity and Specificity; D000099065:Exostosin 2; D000099058:Exostosin 1
chemical_list: D017931:DNA Primers; D017351:N-Acetylglucosaminyltransferases; D000099058:Exostosin 1; D000099065:Exostosin 2