Methylation status of tumor gene promoters in longitudinal samplesa.

aMethylation status of the promoters of six tumor-related gene in paired oligodendroglial tumors. “1st” and “2nd” indicate the primary (at initial diagnosis) and secondary (after progression) resections, respectively. Diagnoses in bold indicate patients who experienced progression in tumor grade or to a more aggressive phenotype between the first and second resections. Patients with a single diagnosis are those who did not experience progression in tumor grade or phenotype, but whose diagnosis remained stable from the first to the second resection. “+”s indicate samples for which methylation was observed.