In Nature this week, researchers at the Broad Institute, and their collaborators in the US, Canada, and Germany report their whole-exome profiling of 92 medulloblastoma samples and paired normal samples, and their identification of 12 gene mutations they say occurred at statistically significant frequencies. These include both previously known mutations and newly identified recurrent somatic mutations in the RNA helicase gene DDX3X. The study provides researchers with a list of biomarkers that could possibly be used to detect or treat medulloblastoma, the most common form of malignant brain tumors in children, says International Science Times' Amir Khan. The team found that these pediatric brain tumors mutate at a much lower rate than adult cancers. In a statement, study co-author Scott Pomeroy of Boston Children's Hospital notes that the mutations are clustered in genes that regulate the function of cells' growth pathways, but aren't directly involved in those pathways.
"Doctors used to categorize medulloblastoma patients as either standard or high-risk, depending on biopsy results," Khan adds. "However, more recently, researchers have found that medulloblastoma could be divided into four subcategories based on gene expression, each with survival rates ranging from 20 to 90 percent." Now, Pomeroy says, not only do researchers have a way of stratifying these tumors genetically, they also have a good idea of which gene mutations drive the different subtypes. "For the first time, we'll be able to classify and treat medulloblastoma based on molecular typing, providing the best therapy with the fewest long-term consequences," he adds.