title: Genetic analysis of hereditary multiple exostoses in Tunisian families: a novel frame-shift mutation in the EXT1 gene.
abstract: Hereditary multiple exostoses (HME) is an autosomal dominant orthopaedic disorder most frequently caused by mutations in the EXT1 gene. The aim of the present study is to determine the underlying molecular defect of HME in two multigenerational Tunisian families with 21 affected members and to examine the degree of intrafamilial variability. Linkage analysis was performed using three microsatellite markers encompassing the EXT1 locus and mutation screening was carried out by direct sequencing. In family 1, evidence for linkage to EXT1 was obtained on the basis of a maximum LOD score of 4.26 at theta = 0.00 with D8S1694 marker. Sequencing of the EXT1 revealed a heterozygous G > T transversion (c.1019G>T) in exon 2, leading to a missense mutation at the codon 340 (p.Arg340Leu). In family 2 we identified a novel heterozygous 1 bp deletion in the exon 1 (c.529_531delA) leading to a premature codon stop and truncated EXT1 protein expression (p.Lys177LysfsX15). This mutation was associated with the evidence of an intrafamilial clinical variability and considered to be a novel disease-causing mutation in the EXT1 gene. These findings provide additional support for the involvement of EXT1 gene in the HME disease.
authors.affiliation: Department of Molecular Immuno-Oncology, Faculty of Medicine, University of Monastir, Monastir, Tunisia.
authors.forename: Sana
authors.initials: S
authors.lastname: Sfar
authors.forename: Abderrazak
authors.initials: A
authors.lastname: Abid
authors.forename: Wijden
authors.initials: W
authors.lastname: Mahfoudh
authors.forename: Houyem
authors.initials: H
authors.lastname: Ouragini
authors.forename: Farah
authors.initials: F
authors.lastname: Ouechtati
authors.forename: Sonia
authors.initials: S
authors.lastname: Abdelhak
authors.forename: Lotfi
authors.initials: L
authors.lastname: Chouchane
mesh_terms: D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D005097:Exostoses, Multiple Hereditary / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics* / Q000378:metabolism; D010375:Pedigree; D017422:Sequence Analysis, DNA; D014416:Tunisia; D000099058:Exostosin 1
chemical_list: D017351:N-Acetylglucosaminyltransferases; D000099058:Exostosin 1