Prognostic significance of retinoblastoma gene mutation in retinoblastoma eye with respect to pathological risk factors

Abstract

Retinoblastoma (Rb) was reported firstly by Benedict is the commonest pediatric intra ocular malignant tumor in children younger than 5 years of age. The study was conducted to detect the RB-1 gene for prognostic evaluation in retinoblastoma and to see the frequency of RB-1 gene in our population. This was a retrospective descriptive analytical study. Five years biopsies (January, 2006 to December 2011) of the retinoblastoma, from the Pathology department, was retrieved to see optic nerve involvement in all the retrieved specimens. The study was taken to see the mutation of RB1 gene by immunohistochemistry and PCR. The study plan was approved from Institutional Review Board (IRB) of the University. All the cases showed positivity of abnormal Rb-1 gene proteins expression by Immunohistochemistry staining. On PCR , 51/52 (98%) tumors expressed gene mutation as compared to 100% expression shown by IHC. Out of these, 28/51 (55%) cases showed ONI and ODI with positivity for mutated RB gene . A positive association was seen among RB gene mutation with ONI and ODI (p = 0.05). There were 33/51 (65%) cases who did not show any EOE but showed PCR positivity for RB gene mutation. While there were 18/51 (35%) cases who showed EOE and positivity of PCR for Rb-1 gene mutation and a positive association was seen with EOE and gene mutation (p = 0.005). The most common sequence of mutation was on 13 with 33 cases for double mutation, 12 cases for single and 6 patients for triple pattern of mutation. Most of the double and triple sequences of mutations were associated with ONI , ODI and EOE . We concluded that mutation of RB-1 gene is responsible in causation of the tumors with a positive association with tumor size and tumor extension ( optic nerve, and extraocular extension ), and mutation affects patients with all ages, both gender and unilateral and bilateral tumors.