title: Alterations in the SMARCB1 (INI1) tumor suppressor gene in familial schwannomatosis.
abstract: Schwannomatosis is a third major form of neurofibromatosis that has recently been linked to mutations in the SMARCB1 (hSnf5/INI1) tumor suppressor gene. We analyzed the coding region of SMARCB1 by direct sequencing and multiplex ligation-dependent probe amplification (MLPA) in genomic DNA from 19 schwannomatosis kindreds. Microsatellite markers in the SMARCB1 region were developed to determine loss of heterozygosity (LOH) in associated tumors. We detected four alterations in conserved splice acceptor or donor sequences of exons 3, 4 and 6. Two alterations that likely affect splicing were seen in introns 4 and 5. An additional four alterations of unclear pathogenicity were found to segregate on the affected allele in eight families including two non-conservative missense alterations in three families. No constitutional deletions or duplications were detected by MLPA. Nine of 13 tumors examined showed partial LOH of the SMARCB1 region consistent with 'second hits.' Alterations were detected in tumors both with and without somatic NF2 gene changes. These findings support the hypothesis that SMARCB1 is a tumor suppressor for schwannomas in the context of familial disease. Further work is needed to determine its role in other multiple and single tumor syndromes.
authors.affiliation: Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Boyd
authors.forename: M J
authors.initials: MJ
authors.lastname: Smith
authors.forename: L
authors.initials: L
authors.lastname: Kluwe
authors.forename: A
authors.initials: A
authors.lastname: Balogh
authors.forename: M
authors.initials: M
authors.lastname: Maccollin
authors.forename: S R
authors.initials: SR
authors.lastname: Plotkin
mesh_terms: D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D015331:Cohort Studies; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005190:Family; D018628:Gene Dosage; D016515:Genes, Neurofibromatosis 2; D016147:Genes, Tumor Suppressor; D006801:Humans; D018895:Microsatellite Repeats; D009442:Neurilemmoma / Q000235:genetics* / Q000378:metabolism; D000071796:SMARCB1 Protein; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; D014157:Transcription Factors