What is retinoblastoma ?
Retinoblastoma is a cancerous tumor of the eye often seen in young children. Retinoblastoma may spread to the brain and other organs such as the liver. It may cause death if not treated. Retinoblastoma accounts for 3 percent of all childhood cancers. Retinoblastoma is a rare tumor and is seen in one in 15,000 to 18,000 live births.
What are the causes ?
Retinoblastoma occurs due to an uncontrolled growth of primitive cells of the retina, the inner light sensitive layer of the eye. The primitive retinal cells differentiate to form various cells present in retina. The primitive retinal cells become cancerous and multiply in uncontrolled fashion to form retinoblastoma. Primitive retinal cells disappear after three years of age, which is why retinoblastoma occurs primarily in young children.
Retinoblastoma occurs due to a mutation in a gene present on chromosome 13, called the RB1 gene. The mutation can be inherited (can be passed through generations) or non-heritable. Forty percent of cases of retinoblastoma are heritable. The mutation in heritable retinoblastoma is passed from parents or occurs in the womb’s cells. Heritable retinoblastoma usually affects both eyes and is associated with other cancers such as osteosarcoma (bone cancer), cancers in the brain and lungs, and melanoma (cancer of pigmented cells of skin).
Risk factors of heritable retinoblastoma include a history of retinoblastoma in parents or siblings. Advanced age of the father is also found to be a risk factor.
Non-heritable retinoblastoma occurs due to a mutation in a primitive retinal cell. It usually affects one eye and is not transmitted to children.