A Comprehensive Genotype-Phenotype Study in 203 Individuals with Retinoblastoma

Abstract

Retinoblastoma is the most common intraocular tumor in children and is caused by biallelic inactivation of the RB1 gene. The identification of RB1 germline variants in patients with retinoblastoma and their families is critical for early diagnosis and prevention. In this study, genetic testing was conducted on the genomic DNA of 203 patients with retinoblastoma using a combined approach of direct sequencing and multiplex ligation-dependent probe amplification (MLPA) assays for genotype-phenotype correlation studies. Sixty-five germline variants were identified in 80 of the 203 patients, with 67 bilateral and 13 unilateral retinoblastoma cases. The variant detection rates in the bilateral and unilateral cases were 88% and 10%, respectively. Eighteen novel variants were identified. Variants were classified according to their presence, mutation pattern, location, molecular consequences, and pathogenicity. Subsequently, the genotypes and phenotypes of the 203 patients were evaluated. Variants were associated with age at diagnosis (p<0.001), laterality (p<0.001), and tumor size (p=0.010). The molecular consequences of the variants were related to laterality (p<0.001) and tumor size (p=0.001). The pathogenicity of the variants was associated with age at diagnosis (p=0.001), laterality (p=0.0212), treatment response (p=0.0470), and tumor size (p=0.002). These results suggest that patient phenotypes are associated with the inherent characteristics of germline RB1 variants. These findings indicate the potential application of genetic testing results in clinical practice.