Retinoblastoma (RB) is a tumor that occurs in the retina of the eye while it is developing. Some RBs are present at birth, and most occur before the age of 5.
They can be in one eye (unilateral) or both eyes (bilateral). About 60 percent are unilateral, while 40 percent are bilateral.
RB is caused by mutations in the RB1 gene, but is not necessarily hereditary. Bilateral RBs are more likely to be hereditary, and can therefore be passed down through different generations in your family. If an RB is not hereditary, the risk to other family members is very low.
Individuals with hereditary RBs also have an increased risk to develop rare brain tumors of the pineal gland and cancers of the bone, soft tissue, and skin, usually in adolescence or adulthood. Identifying which children have hereditary RB1 mutations can help prevent damage from tumors that have not yet occurred.
Most, but not all, forms of hereditary RB1 mutations can be detected using genetic testing. It is still possible to have a hereditary form of RB if no genetic mutation is found. Any individual with bilateral RB is assumed to have hereditary RB, even if there is no identifiable mutation.
If a mutation is identified, testing of young relatives is indicated to determine if they are at high risk to develop RB and other tumors. About 10 percent to 17 percent of people with unilateral RB have the hereditary form.
It is now possible to help preserve sight in patients with RB.