ETV1 and medulloblastoma: To quantify copy number heterogeneity of ecDNA in medulloblastoma, we established an automated image analysis pipeline to estimate the distributions of copy number per cell in interphase FISH microscopy imaging and applied it to four primary medulloblastoma tumors harboring ecDNA: MB036 (MYCN), MB177 (MYCN), MB268 (MDM4) and RCMB56 (DNTTIP2, KMT2E, ETV1).