Calmodulin-like skin protein (CLSP), a secretory peptide, inhibits neuronal death linked to AD in vitro (18) and the transgenic overexpression of the CLSP gene reverses hippocampal synaptic loss and memory impairment in a mouse line named APPswe/PSEN1dE9 mice that transgenically overexpressing two familial AD-causative genes, human amyloid precursor protein with the Swedish mutation and deletion of exon 9 of human presenilin-1 genes (19). This evidence concerns the gene PSEN1 and Alzheimer disease.