Wnt/Wingless Pathway Activation and Chromosome 6 Loss Characterise a Distinct Molecular Sub-Group of Medulloblastomas Associated with a Favourable Prognosis

The accurate assessment of disease risk remains a major goal in children with medulloblastoma. Activation of the canonical Wnt/Wingless (Wnt/Wg) signalling pathway occurs in up to 25% of cases and is associated with a favourable disease outcome. To explore the molecular pathogenesis of Wnt/Wg-active medulloblastomas, and to investigate any genetic basis for their observed clinical behaviour, we assessed a series of primary medulloblastomas for evidence of Wnt/Wg pathway activation, alongside a genome-wide analysis of associated copy-number aberrations. Cases displaying evidence of Wnt/Wg activation (CTNNB1 mutation and/or β-catenin nuclear stabilisation) were exclusively associated with a distinct genomic signature involving loss of an entire copy of chromosome 6 but few other aberrations (p