Comprehensive genetic and epigenetic analysis of sporadic meningioma for macro-mutations on 22q and micro-mutations within the NF2 locus

Table 3 NF2 gene mutation frequencies in meningiomas of different histological subtypes.

Histological subtype	Total no.	NF2 gene mutation frequency¹	Chr. 22 deletions affecting the NF2 gene	Biallelic inactivation of the NF2 gene
Meningothelial	33	6/33 (18%)	13/33 (39%)	6/33 (18%)
Transitional	31	13/31 (42%)	20/31(65%)	12/31(39%)
Fibroblastic	21	11/21 (52%)	18/21 (86%)⁴	11/21 (52%)⁵
Anaplastic	8	5/8 (61%)²	5/8 (61%)	4/8(50%)
Psammomatous	4	2/4 (50%)³	3/4 (75%)	2/4 (50%)
Unclassified	3	1/3 (33%)	1/3 (33%)	1/3 (33%)
Overall	100	39	60	36

1 The methylation status of NF2 gene promoter in tumor M104 is not included.
2 The two micro deletions (1 bp and 7 bp) detected in M169 within exon 12 are considered as one.
3 Two point mutations were detected in M22, only one is used for calculations.
4 Fifteen of the 18 fibroblastic meningiomas that display deletions on chromosome 22 are monosomy cases. The three remaining tumors (M64, M32, and M114) all disclose a minimum of 18 Mb deletion of 22q.
5 Case M64 (biallelic deletion affecting the NF2 gene) is not included in this calculation

ISSN: 1471-2164