Germline partial chromosomal deletions of the entire RB1 gene (13q deletions), account for 6% of the RB1 mutational spectrum. The authors report the rare case of one patient with suspected bilateral iris heterochromia who actually had iris hypoplasia (often masquerading as heterochromia) and bilateral retinoblastoma, due to 13q deletion syndrome. [J Pediatr Ophthalmol. 2018;55:e10-e13.].