2076 Background: LGG are classified according to the WHO as being astrocytoma (DA), oligodendroglioma (OD) or mixed glioma (OA). TP53 mutation and 1p19q codeletion have been the main molecular abnormalities recorded to date. Although IDH1/2 mutations have been described in up to 85% of LGG, IDH negative gliomas do occur. It has recently been found that ATRX plays a significant role in glioma oncogenesis. Methods: We searched for P53 and Olig2 protein expression, MGMT methylation status (pMGMT), 1p19q codeletion and IDH/ATRX status in 63 Colombian LGG patients (pts). Overall survival (OS) rate was estimated and compared between groups and according to genotype. Results: Mean age was 40.1-yo (±12.3), 50% of the pts were male, mean lesion diameter was 41.7 mm (±17.2 mm) and histological distribution was 61.9%, 25.4% and 12.7% for AD, OD and OA, respectively. Surgical resection was total in 47.6%, subtotal in 31.7% and biopsy was performed in 20.6% of the cases. Alterations in IDH1/2 were found in 57.1%, pMGMT+ in 65.1%, overexpression of p53 and Olig2 in 30.2% and 44.4%, and 1p19q codeletion in 34.9%. The presence of alterations in ATRX was analysed in 25 patients, being positive in 16% (all IDH1+/1p19q-). Median follow-up was 15.8 months (95%CI 7.6-42.0), OS was 39.2 months (95%CI 2.5-274) and the variables positively modifying OS were pMGMT+ (p=0.004), 1p19q codeletion (p=0.015), the extension of surgical intervention (p=0.011) and the number of lobes involved (p=0.021). Multivariate analysis showed that pMGMT and 1p19q codeletion modified the OS in our population (p=0.039 and 0.047, respectively). Conclusions: This is the first study which has evaluated the molecular profile in LGG pts from Latin-America. Our findings confirmed the prognostic relevance of pMGMT and 1p19q codeletion, without finding a positive relation for IDH1/2 mutations. This finding could have been explained by sample size and selection bias. Mutations in ATRX are limited to the population of pts having AD/OA and IDH1+/1p19q-.