RB1 and retinoblastoma: In 27 RB cases aged >12months old (23 cases were 12-36months old and 4 cases were 36-60 months old), RB1 gene pathogenic variants were found in 16 of 27 children (59.3%), including 10 of frameshift pathogenic variants or excluding deletion or loss of heterozygosity (62.5%, 10/16), and 6 cases were germline inheritance (2 unilateral RB cases and 4 bilateral/trilateral RB cases) (37.5%, 6/16), as shown in Tables 6 and 7.