Final answer:
An individual with the APOE-4 marker is at a higher risk of developing Alzheimer's disease but is not guaranteed to get the disease. The APOE-4 gene increases the likelihood but many other factors contribute to the disease's development. APOE-4 is not directly linked to a higher risk of vascular neurocognitive disorder.
Step-by-step explanation:
Having the APOE-4 marker means that a person is at higher risk for developing Alzheimer's disease but does not guarantee they will get the disease. Alzheimer's disease can be influenced by a variety of genetic factors, and while the APOE-4 variant in the risk gene apolipoprotein E (APOE) is associated with a greater likelihood of developing late-onset Alzheimer's, it is not determinative of the disease. Other genes and environmental factors also play a role.
The presence of APOE-4 does not indicate a higher risk of vascular neurocognitive disorder directly, but rather, it is specifically linked to Alzheimer's disease risk. Furthermore, some relatives of Alzheimer's might share pathological features, but this does not equate to an increased risk of developing such disorders in APOE-4 carriers without additional factors being present.
It is important to note that risk genes such as APOE-4 do not guarantee that a person will develop dementia related to Alzheimer's disease. This represents a distinction between a predisposition to a condition and the certainty of its occurrence, underscoring the complexity of genetic contributions to neurodegenerative diseases like Alzheimer's.