Fig. 1.

Gene expression profiles for 13 primary adult MBs display 3 subgroups with distinct demographics and histology. (A) Unsupervised hierarchical clustering of 13 adult medulloblastomas based on 1300 transcripts with high standard deviation. Hierarchical clustering is performed using average linkage and dissimilarity based on the Pearson correlation metric. Clinical features of the study population are indicated below the dendrogram: sex (male, black; female, white), age at diagnosis (18–20 y, red; 20–40 y, white; >40 y, black), histology (C, white; DN, black; LC/A, red), M stage (M0, white; M+, black), risk (low, white; high, black), and progression and death (no event, white; event, black). (B) Application of consensus non-negative matrix factorization (NMF), an unsupervised bioinformatics tool for determining the number of independent classes within an expression dataset, strongly supports the existence of 3 adult medulloblastoma subgroups.