In addition to APP, other genes and noncoding RNAs on chromosome 21 could also contribute to DS-AD neuropathology, such as BACE2 (23), CTSB (24), DYRK1A (25), ETS2 (26), RCAN1 (27), SUMO3 (28), and miR-155 (29). The gene discussed is CTSB; the disease is Alzheimer disease.