Alzheimer’s is a neurodegenerative disease involving progressive memory loss and other declines in brain function. One common cause of familial Alzheimer’s is mutation in the PSEN1 gene. This gene encodes a protein that cleaves certain intracellular peptides which, once free in the cytoplasm, promote CBP<nowiki/>degradation. Mutations in PSEN1 decrease its production or ability to cleave proteins. This derepresses the CBP proteins, and allows them to perform their function of upregulating transcription of their target genes.