APP and Alzheimer disease: One example of alternative isoform production has been found in AD where the asRNA 51A maps to the first intron of Sortilin-related receptor 1 (SORL1) and, by pairing with its pre-mRNA, drives a splicing shift of SORL1 from the canonical full-length protein form to an alternatively spliced shorter protein variant that is associated with an impaired processing of the amyloid-precursor protein (APP) [50].