Specific gene mutations clustered neatly into the four molecular subtypes, although the majority of genes (88 percent) were mutated only once in the entire tumor collection. Only 12 genes were mutated in more than one tumor, illustrating medulloblastoma's genetic heterogeneity.

Dr Pomeroy also highlighted that, "The results reflect two emerging genetic themes seen throughout childhood tumors. First, very low mutation rates, much lower than those seen in adult tumors, and second, the importance of mutations in genes that regulate the function of the cell's growth pathways but which aren't direct components of those pathways."

The study was supported by grants from the National Human Genome Research Institute , the National Cancer Institute, the National Institute of Neurological Disorders and Stroke, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the Canadian Institutes of Health, German Cancer Aid, St Baldrick's Foundation, the Mullarkey Research Fund, the Pediatric Brain Tumor Foundation and the Howard Hughes Medical Institute.