RB1 and retinoblastoma: Among children with heritable retinoblastoma, children heterozygous for a pathogenic RB1 variant (median: 0.6 years, Interquartile range: 0.9 years) showed a non-significant trend for a younger age at diagnosis than children with somatic mosaicism (median 1.4 years, Interquartile range: 2.9, pMann-Whitney-U-Test = 0.06) (Figure 4).