Alzheimer's Disease

what type of mutation is alzheimer’s disease ?

i need to know if it is a gene mutation or a chromosomal mutation, and what type.
i have not found anything searching the internet, so please help!

Both- read on From first link ***Alzheimers is caused by mutations in three genes. The first mutation to be identified is in the amyloid precursor protein (APP) gene located on chromosome 21. APP is cleaved to form amyloid, a major component in amyloid plaques. Chromosome 21 was viewed as a likely site for Alzheimer’s disease-causing mutations for two reasons: … Continue Reading