1. Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suarez, 14269 Ciudad de México, DF, Mexico
2. Department of Otolaryngology, “La Paz” University Hospital, 28046 Madrid, Spain
3. Unidad de Investigación, Laboratorio Oncogenetica Molecular, “La Paz” University Hospital, 28046 Madrid, Spain
4. Department of Pathology, “La Paz” University Hospital, 28046 Madrid, Spain
5. Brain Tumor Biology Unit, CIFA, University of Navarra School of Sciences, 31009 Pamplona, Spain