GENETICS

Researchers have not found a specific gene that directly causes late-onset Alzheimer’s disease as it arises from complex changes in the brain over decades, but inheriting one or two alleles of apolipoprotein-E called APOE ε4 in chromosome 19 is associated with a higher risk of disease. Earlier onset of disease between the 30s and mid-60s is also reported on people who inherited mutations of:

1. Amyloid Precursor Protein (APP) on chromosome 21.

2.  Presenilin-1 (PSEN1) on chromosome 14

3. Presenilin-2 (PSEN2) on chromosome 1.

 

Most people with Down syndrome also develop Alzheimer’s disease because they have an extra copy of chromosome 21 (NIA, 2019).