The age at which children were diagnosed with RB1−/− retinoblastomas in cluster C (median: 2.86 years) did not statistically differ from children with cluster B retinoblastomas (median: 2.36 years, pWilcoxon rank Test = 0.83; Supplementary Fig. S2d), while the 6 patients with RB1-proficient retinoblastomas in cluster C were significantly younger (median: 0.38 years, vs cluster B pWilcoxon rank test = 0.006961; Supplementary Fig. S2d). Here, RB1 is linked to retinoblastoma.