Taken together, 12 patients that inherited RB1 mutations in the families without familial history of retinoblastoma (Table 2), and two patients from the families with familial history but without clinical signs of the disease in the probands’ parents (## 261 and 319; Figure 1), constituted a cohort of 14 patients who inherited RB1 mutations from their clinically asymptomatic mutation carrier parents, nine from fathers and five from mothers (Figure 2). Here, RB1 is linked to retinoblastoma.