APP and Alzheimer disease: In the transgenic mouse model of AD carrying APP Swedish mutation and PSEN1 lacking exon 9 (APPswe/PSEN1Δ9), OS-associated miR-34a, miR-34c, and miR-98 are abnormally expressed in the animal between 3 and 6 months of age [128] when initial Aβ depositions start in the hippocampus [129].