title: Biallelic inactivation of NF1 in a sporadic plexiform neurofibroma.
abstract: Plexiform neurofibromas are a major cause of morbidity in individuals with neurofibromatosis type 1 (NF1). Sporadically, these tumors appear as an isolated feature without other signs of NF1. A role for the NF1 gene in solitary plexiform neurofibromas has never been described. In this study, we report a 13-year-old boy who was diagnosed with a plexiform neurofibroma, without other NF1 diagnostic criteria. The tumor was partially resected and analyzed using different techniques: karyotyping, fluorescence in situ hybridization (FISH), and microarray comparative genomic hybridization (aCGH). Tumor Schwann cell culture and subsequent karyotyping showed a rearrangement involving chromosomes 1 and 17, namely an insertion of chromosomal bands 1p36-35 at 17q11.2. FISH demonstrated that the insertion interrupted the NF1 gene. In addition, a deletion was detected affecting the other NF1 allele. Whole-genome aCGH analysis of the resected tumor confirmed the presence of an 8.28 Mb deletion including the NF1 gene locus in ∼15-20% of tumor cells. We conclude that biallelic NF1 inactivation was at the origin of the isolated plexiform neurofibroma in this patient. The insertion is most likely the "first hit" and the large deletion the "second hit."
authors.affiliation: Department of Human Genetics, KU Leuven, Leuven, Belgium.
authors.forename: Eline
authors.initials: E
authors.lastname: Beert
authors.forename: Hilde
authors.initials: H
authors.lastname: Brems
authors.forename: Marleen
authors.initials: M
authors.lastname: Renard
authors.forename: Julio Finalet
authors.initials: JF
authors.lastname: Ferreiro
authors.forename: Cindy
authors.initials: C
authors.lastname: Melotte
authors.forename: Reinhilde
authors.initials: R
authors.lastname: Thoelen
authors.forename: Ivo
authors.initials: I
authors.lastname: De Wever
authors.forename: Raf
authors.initials: R
authors.lastname: Sciot
authors.forename: Eric
authors.initials: E
authors.lastname: Legius
authors.forename: Maria
authors.initials: M
authors.lastname: Debiec-Rychter
mesh_terms: D000293:Adolescent; D000483:Alleles; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D018318:Neurofibroma, Plexiform / Q000235:genetics* / Q000473:pathology; D025542:Neurofibromin 1 / Q000235:genetics*; D017384:Sequence Deletion
chemical_list: D025542:Neurofibromin 1