Diamniotic, dichorionic, male in vitro fertilisation (IVF) twins were born at 26+6 weeks. Retinopathy of prematurity screening revealed bilateral posterior pole retinoblastoma in twin A at 34 weeks' gestation. Aggressive chemoreduction therapy regressed the tumours significantly, which await definitive treatment (figure 1). Genetic analyses identified a heterozygous mutation in the RB1 gene in the affected twin that was absent …