Overview of RB gene mutations in patients with retinoblastoma: Implications for clinical genetic screening

Objective: This study aimed to determine the distribution of germline mutations in the retinoblastoma (RB) gene in patients with retinoblastoma to design more effective genetic testing. Design: A meta-analysis. Participants: 192 cases identified from literature. Methods: All identifiable reported cases of bilateral retinoblastoma, which included DNA sequence analysis of the RB gene, were reviewed. Main Outcome Measure: Type of genetic mutation. Results: Among 192 patients with retinoblastoma with identifiable germline mutations in the RB gene, the DNA alteration was a nonsense mutation in 83 (43%), frameshift in 67 (35%), intron mutation in 23 (12%), missense mutation in 11 (6%), in-frame deletion in 5 (3%), and promoter mutation in 3 (2%). Mutations were distributed throughout 24 of the 27 exons of the RB gene with no single mutational 'hotspur.' Exons 8, 17, 18, and 23 were involved most often, and 189 (98%) of the mutations were predicted to affect the RB large pocket domain. Conclusions: A single genetic test is unlikely to detect all germline RB gene mutations in patients with retinoblastoma because of the variety of types and locations of mutations that occur. However, a series of complementary tests may be able to rapidly detect mutations based on the observation that most mutations alter the protein size and disrupt the large pocket domain.