Until recently no conclusive functional differences have been ascribed to these different isoforms apart from the protease inhibitor role of the Kunitz-type protease inhibitor (KPI) domain encoded by exon 7; nevertheless, efficiency of Aβ production appears to be affected by the APP isoform13, 14, 51 and alterations in neuronal splicing of APP have been observed in the brain of AD patients, with numerous studies reporting a decrease in neuronal APP695 along with an increase in full-length APP7709, 10, 11, 12. This evidence concerns the gene APP and Alzheimer disease.