GPT and neuroblastoma: For an independent validation, we compared the expression levels of H3F3B and H2AFJ between 130 telomeric c-circle positive and negative neuroblastomas from Hartlieb et al.,31 and found significantly higher expression of H3F3B (p = 3.01 × 10−4, ANOVA) and H2AFJ (p = 0.02, ANOVA) in c-circle positive tumors, confirming their upregulation in ALT (Figure S20).