Background: Retinoblastoma (RB) is a common neoplastic disease in children, leading to high mortality if not diagnosed and treated timely. Mutations in both versions of the Retinoblastoma1 (RB1) gene are responsible for this disease. A wide range of mutations has been reported throughout the RB1 gene. Objectives: The present study aimed to assess the concordance of paternal and maternal RB-1 gene mutation with clinical manifestation and disease staging in patients suffering from RB. Methods: This cross-sectional study was performed on 23 patients with unilateral or bilateral RB. Paternal and maternal peripheral blood samples were extracted for genome analysis. Information related to clinical manifestations and disease staging was collected from the patients’ hospital records. Multiplex-ligation dependent probe amplification (MLPA) method or Sanger sequencing method was employed to assess the gene mutation and its genomic pattern. Results: No significant association was revealed between the presence of both maternal and paternal RB1 gene mutations and the disease staging, while the study could show a significant relationship between the presence and heterozygous pattern of RB1 gene mutation and the presence of disease-related clinical manifestations that bilateral involvement was strongly associated with the presence of a heterozygous pattern of gene mutation compared to unilateral involvement (P = 0.001). Conclusions: This study showed a significant correlation between the presence of RB1 gene mutation and bilateral involvement in RB, but the association between the disease staging and gene mutation remains insignificant.