7. 1. Risk genes increase the likelihood of developing a disease,
but do not guarantee it will happen. Researchers have found
several genes that increase the risk of Alzheimer’s.
apolipoprotein E-e4, or APOE-e4, is the first risk gene
identified and remains the one with strongest impact.
2. Deterministic genes directly cause a disease, guaranteeing
that anyone who inherits one will develop the disorder.
Scientists have discovered variations that directly cause
Alzheimer’s disease in the genes coding three proteins:
amyloid precursor protein (APP), presenilin-1 (PS-1) and