Discordant Retinoblastoma in Monozygotic Twins Due to Deletion of 13Q14

Purpose To report discordant retinoblastoma in monozygotic twins, confirmed by GeneScan. Methods One twin presented unilateral retinoblastoma that was treated with enucleation; the other twin had no retinoblastoma. To confirm monozygosity, DNA from leukocytes was analyzed through GeneScan with highly polymorphic markers; to exclude 13q14 deletion, FISH analysis was performed in leukocytes and oral cells of both twins and their parents and in...