Final answer:
The majority of Alzheimer's disease cases are not strictly caused by gene mutations. While early onset Alzheimer's is linked to specific gene mutations, late-onset Alzheimer's has a more complex genetic and environmental risk profile. Genetic research continues to explore the relationship between genes and Alzheimer's disease.
Step-by-step explanation:
While a small percentage of Alzheimer's disease cases are caused by mutations in specific genes related to early onset Alzheimer's, the majority of cases are not solely the result of gene mutations. Early onset Alzheimer's, which begins between the ages of 30 and 60, is linked to mutations in one of three genes and affects less than five percent of patients. Late-onset Alzheimer's, which is more common, also has a genetic component, with the APOE gene's E4 variant being a well-known risk factor. However, risk genes do not guarantee the development of Alzheimer's, and environmental factors may also play a significant role in the disease.
Extensive research, including an international analysis of over 50,000 individuals, has identified several genes that increase the likelihood of developing Alzheimer's in the elderly. This research offers clues about the disease's initiation and progression. Nonetheless, environmental factors and genetic testing considerations, such as the advantages and disadvantages of knowing one's genetic risk, remain topics of discussion.