OBJECTIVEMultiple meningiomas are uncommon brain tumors occurring concurrently in several intracranial locations in the same patient. In the present study, we determined the clonality, methylation status of deoxyribonucleic acid, and relationship of genetic alterations in eight meningiomas from one female patient.METHODSSix molecular genetic techniques, including two methylation-based clonality assays and one transcription-based clonality assay, methylation analysis of CpG islands by methylation-specific polymerase chain reaction, loss of heterozygosity, microsatellite instability, and mutational analysis of theNF2gene on chromosome 22, were used in comparative investigations on clonality and genetic alterations.RESULTSThe presence of clonal tumor cells was demonstrated by 1) loss of the same copy of chromosome 22 in all eight tumors; 2) transcription of the humanARgene from the same allele in six of eight tumors; 3) a common unmethylated allele at theARlocus in all eight tumors; and 4) the identical single-basepair insertion mutation in exon 9 of theNF2gene in six of eight tumors. In addition, loss of a copy of the X chromosome in one tumor nodule and microsatellite instability in another nodule were observed.CONCLUSIONTaken together, this case of multiple meningiomas was most likely monoclonal in origin. Loss of chromosome 22 was an early event during the development of multiple meningiomas and was followed by mutations at theNF2locus. Later events, including loss of the X chromosome, variation ofARgene expression, or microsatellite instability, may also have played a role in the development of multiple meningiomas in this patient.