Snap Shot A 3-year-old child presents strabismus. His mother notes that sometimes of family photographs it appears that one eye is white while the other is red. Introduction Definition malignancy of the retina of the eye often presents in children less than 3 years of age Genetics Rb is a tumor suppressor gene located on chromosome 13 loss of heterozygosity both alleles must be deleted/mutated before the development of cancer and expression of disease ("two-hit hypothesis") as opposed to oncogenes which require just one mutation mutation in a tumor suppressor gene leads to increased cancer risk inhertied loss of Rb protein results in bilateral disease mechanism regulates cell growth and repair damage see Tumor suppressor gene topic see Cell cycle topic associations familial retinoblastoma is a predisposing factor to the development of osteosarcoma Presentation Symptoms visual loss Physical exam leukocoria absence of red-light reflex unilateral exophthalmos strabismus Evaluation Referral to opthamologist if seen in general pediatric screening Treatment Surgical enucleation of the eye