RB1 and retinoblastoma: ,18,26 Germline mosaicism for g78238C>T (R552X) was detected in one of our patients with bilateral RB (553N100) at the sequencing depth of 490×, whereas an average sequencing depth of RB1 region for all samples was 500×; this mosaic variant has been reported to be associated with maternal transmission causing RB in offspring.29