Final answer:
The APOE gene variant E4 increases the risk of developing Alzheimer's disease. Mutations in genes like APP and tau protein contribute to the formation of amyloid plaques and neurofibrillary tangles.
Step-by-step explanation:
In Alzheimer's disease, the apolipoprotein E (APOE) gene and its variant E4 increase the risk of developing the disease. A carrier of the E4 variant is more likely to develop Alzheimer's compared to someone without the variant. Several other genes have also been identified that may play a role in the development of the disease. Mutations in genes like APP and tau protein are associated with the formation of amyloid plaques and neurofibrillary tangles, which are pathological hallmarks of Alzheimer's.