For example, the Drosophila gene amyloid precursor protein-like (Appl) gene encodes a protein product (APPL) (Rosen et al. 1989) that is orthologous to the human amyloid beta precursor protein (APP) associated with Alzheimer’s disease (Kang et al. 1987). Here, APP is linked to early-onset autosomal dominant Alzheimer disease.