(ChemotherapyAdvisor) – Genetic mutations that cause pediatric brain tumors have been identified, according to an international team of researchers. This conclusion is based on a study entitled “Medulloblastoma exome sequencing uncovers subtype-specific somatic mutations,” which was published online in Nature on July 22.

The investigators based this study on several lines of evidence. First, medulloblastomas are the most common malignant brain tumors in children. Second, limited data are available on the genetic events that drive tumorigenesis, making the development of more effective diagnostic, prognostic, and therapeutic strategies difficult. “Recently, our group and others described distinct molecular subtypes of medulloblastoma on the basis of transcriptional and copy number profiles. Whole-exome hybrid capture and deep sequencing were used to identify somatic mutations across the coding regions of 92 primary medulloblastoma/normal pairs,” the investigators wrote.

The following results were reported. Based on molecular testing, the investigators found that the overall median mutation rate of medulloblastoma was 0.35 non-silent mutations per megabase, which is low and consistent with other pediatric tumors. In their genetic screen, the investigators identified 12 genes mutated at statistically significant frequencies, including “previously known mutated genes in medulloblastoma such as CTNNB1, PTCH1, MLL2, SMARCA4, and TP53,” they reported. “Recurrent somatic mutations were newly identified in an RNA helicase gene, DDX3X, often concurrent with CTNNB1 mutations, and in the nuclear co-repressor (N-CoR) complex genes GPS2, BCOR and LDB1.”

Continue Reading

The investigators concluded that the alteration of several genes and gene pathways across medulloblastomas, and within specific subtypes of this disease, illustrates the genetic complexity and heterogeneity of the disease.