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Updated: Apr 5, 2026
Reconstruct Human Retinoblastoma In Vitro
Published on: October 11, 2022
Knudson's hypothesis revisited in Indian retinoblastoma patients
Namrata Gaikwad1, Ayyasamy Vanniarajan2, Akram Husain2
1Department of Orbit, Oculoplasty and Ocular Oncology, Aravind Eye Hospital, Madurai, India.
Insights
Knudson's two-hit hypothesis for retinoblastoma (RB) was confirmed in Indian patients. Genetic analysis of RB1 mutations in tumor samples supported the hypothesis, linking clinical parameters to genetic alterations in this childhood cancer.
Area of Science:
- Ophthalmology
- Genetics
- Pediatric Oncology
Background:
- Retinoblastoma (RB) is the most common intraocular malignancy in children under 5.
- Understanding the genetic basis of RB is crucial for diagnosis and treatment.
Purpose of the Study:
- To correlate clinical parameters with RB1 gene mutations in Indian RB patients.
- To validate Knudson's two-hit hypothesis in a South Indian cohort.
Main Methods:
- Clinical data from 73 Indian RB patients were analyzed.
- RB1 gene mutation analysis was performed.
- Statistical analysis using Knudson's two-hit hypothesis model was applied.
Main Results:
- Unilateral RB cases showed a mean age of 24 months, bilateral cases 9.8 months.
- Familial RB occurred in 17.8% of patients, predominantly bilateral.
- All patients' data aligned with Knudson's one-hit (bilateral) and two-hit (unilateral) curves, confirmed by genetic analysis.
Conclusions:
- Knudson's two-hit hypothesis is reconfirmed in Indian RB patients.
- Genetic analysis of RB1 mutations provides strong evidence for the two-hit model in RB development.
Aim:
Retinoblastoma (RB) is the most common primary intraocular malignancy affecting children under 5 years of age. This study aims to correlate the clinical parameters with RB1 mutation in the light of Knudson's two-hit hypothesis in Indian RB patients.
Methods:
We analyzed the clinical details of 73 RB patients visiting Aravind Eye Hospital, Madurai, India, between January and October 2012. Data on gender, presenting age and sign, laterality, number of tumors in each eye and family history were collected. A semi log plot was derived based on Knudson's two-hit hypothesis. Genetic analysis of RB1 was carried out to identify the two hits.
Results:
The mean age at diagnosis for unilateral and bilateral cases was 24.0 ± 15.1 and 9.8 ± 11.5 months, respectively. Familial RB was seen in 13 (17.8%) patients of whom 11 were bilateral. Multiple tumors were observed more frequently in bilateral than in unilateral cases. All unilateral and bilateral patients followed the two-hit and one-hit curves, respectively, confirming Knudson's hypothesis in Indian patients. Genetic analysis identified two somatic mutations in tumor samples of sporadic unilateral cases. Among the two bilateral patients, one received the first hit from her father and the other patient developed a de novo germline mutation during early development.
Conclusion:
The two-hit hypothesis has been reestablished in Indian patients. Genetic analysis of tumor samples has also complemented the statistical analysis to reaffirm the two hits in tumor development.
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