Retinoblastoma causes
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
- Retinoblastoma is a cancer of the retina. In children with the heritable genetic form of retinoblastoma there is a mutation on chromosome 13, called the RB1 gene.The defective RB1 gene can be inherited from either parent; in some children, however, the mutation occurs in the early stages of fetal development. Inheritance is autosomal dominant with 90% penetrance.
Causes
- Retinoblastoma is caused by a mutation in a gene controlling cell division, causing cells to grow out of control and become cancerous.
- In a little over half of the cases, this mutation develops in a child whose family has never had eye cancer.
- Other times the mutation is present in several family members. If the mutation runs in the family, there is a 50% chance that an affected person's children will also have the mutation. They will therefore have a high risk of developing retinoblastoma themselves.
- The cancer generally affects children under the age of 6. It is most commonly diagnosed in children aged 1 - 2 years.
- Retinoblastoma occurs in heritable and nonheritable forms
- A child is thought to have the heritable form of retinoblastoma when one of the following is true:
- There is a family history of retinoblastoma.
- There is a certain mutation (change) in the RB1 gene. The mutation in the RB1 gene may be passed from the parent to the child or it may occur at the time of conception.
- There is more than one tumor in the eye or there is a tumor in both eyes.
- There is a tumor in one eye and the child is younger than 1 year.
- After diagnosis and treatment in a child with heritable retinoblastoma, new tumors may continue to form for a few years. Regular eye exams to check for new tumors are usually done every 2 to 4 months for at least 28 months.
- Nonheritable retinoblastoma is retinoblastoma that is not the heritable form. Most cases of retinoblastoma are the nonheritable form.
References