Adult grade II low-grade gliomas (LGG) are classified according to the WHO as 
astrocytomas, oligodendrogliomas or mixed gliomas. TP53 mutations and 1p19q 
codeletion are the main molecular abnormalities recorded, respectively, in 
astrocytomas and oligodendrogliomas and in mixed gliomas. Although IDH mutations 
(IDH1 or IDH2) are recorded in up to 85 % of low-grade gliomas, IDH negative 
gliomas do occur. We have searched for p53 expression, 1p19q codeletion and IDH 
status (immunohistochemical detection of the common R132H IDH1 mutation and IDH 
direct sequencing). Internexin alpha (INA) expression previously recorded to be 
associated with 1p19q codeletion (1p19q+) gliomas was also analysed. Low-grade 
gliomas were accurately classified into four groups: group 1, IDH+/p53-/1p19q-; 
group 2, IDH+/p53-/1p19q+; group 3, IDH+/p53+/1p19q-; and group 4, triple 
negative gliomas. In contrast to the WHO classification, this molecular 
classification predicts overall survival on uni- and multivariate analysis (P = 
0.001 and P = 0.007, respectively). Group 4 carries the worst prognosis and 
group 2 the best. Interestingly, p53 +/INA- expression predicts lack of 1p19q 
codeletion (specificity 100 %, VPP 100 %). The combined use of these three 
molecular markers allow for an accurate prediction of survival in LGG. These 
findings could significantly modify LGG classification and may represent a new 
tool to guide patient-tailored therapy. Moreover, immunohistochemical detection 
of p53, INA and mR132H IDH1 expression could represent an interesting 
prescreening test to be performed before 1p19q codeletion, IDH1 minor mutation 
and IDH2 mutation detection.