👉 Retinoblastoma is a rare type of tumor that starts in the retina (the part of the eye that helps us see). It's usually caused by mutations in genes called BRCA1 and BRCA2, which are important for cell division. This can lead to cancerous growths called retinoblastomas. The exact cause of retinoblastoma is unknown, but it's thought to be related to a mutation that affects DNA repair processes. Retinoblastomas
