Given the task definition and input, reply with output. In this task, you will be given a sentence. You need to reconize the name of the disorder or disease. Disease is a disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury. Although there might be several correct answers, you need to write one of them.

 We have used single strand conformation polymorphism analysis to study the 27 exons of the RB1 gene in individuals from a family showing mild expression of the retinoblastoma phenotype .

retinoblastoma