Given the importance of Aβ deposition in AD, accounting for the role of APP, and knowing that the cornea represents an interesting structure to analyze due to its easy access, studies in humans are mandatory to evaluate predictive AD biomarkers that may be present in AD corneas—not only Aβ, but also others, such as tau protein, nerve growth factor (NGF), and acetylcholine. The gene discussed is APP; the disease is Alzheimer disease.