[The molecular genetics of meningiomas and genotypic/phenotypic correlations]

The WHO classification divides meningiomas in three grades. In grade 1 tumors, by far the most common (90 p. cent), inactivation of the NF2 gene (associated to the loss of chromosome 22) is the most frequent alteration. However, a subset of grade 1 meningiomas does not involve the NF2 gene and is less likely to evolve towards higher grade tumors. After NF2 inactivation, additional events may occur and are related to greater aggressiveness, such as loss of 1p, 14q, 10 q and 9p chromosomes, reactivation of telomerase, inactivation of the p16/CDKN2A gene. All these alterations are much more frequent in grades 2 (atypical) and 3 (malignant) of the WHO classification. In addition to reviewing the available literature, we pooled together the individual cases in order to refine the correlation between genotype and phenotype (histological grading, location) and to propose a model for tumoral progression of meningiomas.