APP and Alzheimer disease: For instance, miARNs 106a, 502c, -106b and 17-5p could potentially downregulate the expression of the APP gene, and decreased expression of miR-29a and miR-29b-1 in AD patients has been correlated to higher expression of the BACE1 gene, which encodes an enzyme that limits the production of beta-amyloid peptide [136].