APP and Alzheimer disease: It is tempting to speculate that this finding, if confirmed with larger samples, would support the possibility that APP is at least partially regulated by an L1 element that is undergoing somatic transposition and copy number expansion in AD brains, as a result of LINE1-expressed reverse transcriptase [149–151]—but this finding is still hotly questioned [152]—or via LINE1-mediated overexpression of APP from a germline program [28, 153–160].