[Gliomas: the role of environmental risk factors and genetic predisposition].

Exposure to ionising radiation is the only established risk factor for glioma. Although gliomas are looked upon as a non-heritable disease, physicians regularly see patients with affected relatives in practice. A few monogenetic tumour syndromes explain < 5% of all gliomas: neurofibromatosis type 1 and 2, Li-Fraumeni syndrome, tuberous sclerosis, Turcot syndrome, Gorlin syndrome, and the melanomaastrocytoma syndrome. Aggregation ofgliomas in families without these tumour syndromes also occurs. The overall familial pattern is generally atypical for hereditary cancers. Relatives are estimated to have a 2- to 9-fold increased risk. The occurrence ofgliomas in families can probably best be explained by a multifactorial model: environmental risk factors with a genetically determined susceptibility for these risk factors. The identity of the genetic variants leading to this predisposition remains to be determined. When there are indications of a hereditary tumour syndrome, additional diagnostic investigation is indicated.