The Retinoblastoma Gene
Dear OncoLink "Ask the Experts,"
I have a question regarding the heredity of retinoblastoma. What gene exactly is the cause and does it have to present in both parents for it to be transmitted to the offspring? I am concerned because I am about to marry a man who had retinoblastoma bilaterally as a child. What is the likelihood that our children will have retinoblastoma?
Please let me know what you think. I have been curious about this for a while.
Kenneth Blank, MD and John Han-Chih Chang, MD, Editorial Assistants for Oncolink, respond:
Dear OncoLink Reader:
Thank you for your question.
The gene involved in retinoblastoma is the called Rb gene. The protein product of this gene plays an integral role in initiating cell division. When the gene is mutated, as occurs in retinoblastoma patients, the control over cell division goes awry leading to uncontrolled cell proliferation and, therefore, tumor formation and growth. No one entirely understands why these tumors form in the eye.
Two forms of retinoblastoma exist; a hereditary form that can be passed to offspring and a non-hereditary form. Approximately 60% of adults have the non-hereditary form and cannot pass the disease to their children. If the parent has the hereditary form there is a 50% risk that his/her offspring will be affected. Adults who had both eyes afflicted with the disease as children are likely have the hereditary form.
You may want to consider looking deeper into your husband's medical records to decide which type he did have. Also, you may both benefit by speaking to a professional licensed genetic counselor.