This video case study explores the approaches scientists used to identify a mutation that causes retinitis pigmentosa (RP), a progressive disease that leads to blindness.

RP results in the deterioration of the retina and loss of vision. Some cases of RP are inherited and caused by mutations in one of several different genes. Many mutations that cause RP have been identified. But when scientists tested the DNA of the patient featured in this video, Sam, they did not find any of these known mutations. The video follows physician-scientist Edward Stone as he tried to uncover the mutation that causes Sam’s RP.

This video incorporates embedded questions at automatic pause points, where students are asked to make predictions, construct explanations, and analyze data. After answering all the questions, students can view their answers in a “Report” that can be printed. They can also add further explanation to each answer in the Report if their thinking has changed. The video can also be shown without embedded questions using "Presentation Mode."