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inSIGHT

Abstract

The retina is essential for vision. It is composed of 10 distinct layers and contains specialized photoreceptor cells, rods, and cones that are responsible for converting photons of light into electrical signals through a process called phototransduction.1 These electrical signals are transmitted to the brain via the optic nerve where they are interpreted as a visual picture.1

Retinoblastoma is a rare but aggressive malignant tumor of the retina and represents the most common intraocular malignancy in the pediatric populabon.2 The disease follows Knudson's two-hit hypothesis and occurs due to biallelic inactivation of the RB1 tumor suppressor gene located on chromosome 13q14.3 Loss of RB1 leads to uncontrolled proliferation of retinal cells. Retinoblastoma may present as either hereditary (germline mutation) or non-hereditary (somatic mutation).3 Approximately 45% of cases are hereditary, while 55% are sporadic.3 The RB1 gene encodes the retinoblastoma protein, a vital tumor suppressor gene and regulator of the cell cycle, responsible for inhibiting the transition from the G1 phase to the S phase.2,4 In the absence of functional RB1 protein, the E2F transcription factor becomes constitutively active, driving the expression of genes involved in DNA synthesis and cell cycle progression.2,4 Additionally, retinoblastoma tumors exhibit increased expression of VEGF to support angiogenesis and overexpression of anti-apoptotic proteins.2

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