Which are the causes of Retinoblastoma?

Retinoblastoma is a rare form of eye cancer caused by mutations in the RB1 tumor suppressor gene, which prevents cells in the retina from dividing uncontrollably. While most cases occur due to sporadic genetic changes after conception, approximately 40% of patients inherit a mutation in this gene, leading to a hereditary form of the disease.

What causes Retinoblastoma at a genetic level?

At the heart of Retinoblastoma lies the RB1 gene, located on chromosome 13. Think of the RB1 gene as a "braking system" for cell division; its job is to send signals to retinal cells to stop dividing once they have reached maturity. When both copies of this gene are mutated or missing, the "brakes" fail, and cells begin to multiply rapidly, forming a tumor. In hereditary Retinoblastoma, an individual is born with one mutated copy of the gene in every cell of their body, making it statistically much easier for the second copy to mutate later, thereby triggering tumor growth.

Is Retinoblastoma hereditary or sporadic?

The etiology of Retinoblastoma is categorized into two distinct forms based on how the genetic mutations are acquired:

• Hereditary (Germline) Retinoblastoma: The mutation is present in the egg or sperm, meaning it is passed down from a parent or occurs very early in embryonic development. These patients often develop tumors in both eyes (bilateral) and are at higher risk for other secondary cancers later in life.


• Non-hereditary (Sporadic) Retinoblastoma: These mutations occur randomly after conception in a single retinal cell. These cases typically result in a tumor in only one eye (unilateral) and are not passed on to offspring.

Are there environmental triggers for Retinoblastoma?

Unlike many other cancers, there is currently no evidence that environmental toxins, diet, or lifestyle factors cause Retinoblastoma. Because the disease is fundamentally a genetic event occurring in the rapid development phase of the retina, research has shifted away from external environmental triggers and toward understanding the precise timing of the "second hit" mutation. While researchers continue to study why these mutations occur in specific individuals, Retinoblastoma remains primarily a disease of genetic miscoding rather than external exposure.

How does current research aim to improve our understanding of Retinoblastoma?

Medical researchers are currently focused on identifying modifiers—other genes that may influence how aggressively Retinoblastoma grows. Current studies are investigating the role of the MYCN gene, which can sometimes be amplified in cases where the RB1 gene is not the only driver of tumor development. By mapping these pathways, scientists hope to develop targeted therapies that can kill tumor cells while sparing the child's vision, moving beyond traditional chemotherapy and radiation.

Next steps

• Consult a pediatric ophthalmologist or an ocular oncologist immediately if you notice a "white glow" (leukocoria) in a child’s pupil.


• Seek a referral to a genetic counselor to discuss family testing if a child is diagnosed with bilateral Retinoblastoma.


• Connect with the 8 members of the DiseaseMaps.org community who have navigated this diagnosis to share experiences and emotional support.


• Participate in clinical registries if recommended by your oncology team to contribute to global research efforts.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Retinoblastoma


• Orphanet: Retinoblastoma (ORPHA:790)


• OMIM (Online Mendelian Inheritance in Man): #180200 Retinoblastoma


• American Academy of Ophthalmology: Retinoblastoma Diagnosis and Treatment