Alzheimer’s disease (AD) is a permanent condition that affects the brain. This condition progressively alters the working of nerve cells and ultimately leads to the death of brain cells. As a result, affected individuals lose the ability to remember even the most important details about themselves and their families. Alzheimer’s disease commonly occurs in individuals aged 65 years and above. Although most of the symptoms of this condition resemble those of the normal aging process, it is not related to natural aging at all and found to be the leading cause of dementia; the loss of logical capabilities. Complications with thinking, recollection, reckoning, and other essential functions can cause day-to-day activities to be more difficult.
(National Academy on an Aging Society, 2000).
It is believed that a combination of genetic and environmental factors play a significant role in the development of this disease. Alzheimer’s often occurs in two distinct forms. The first form is the early onset disease, whereas the second form is the late onset disease. (Alzheimer’s Society, 2007). In early onset, patients display the symptoms of the condition prior to the age of 65, but rather between the ages of 30 to 40. Research suggests that the early onset form is genetically heritable and may affect a number of generations in a family. The probable cause for the development of this form of the disease is a mutation in one of the following genes: the amyloid precursor protein gene (APP) and two presenilin genes (PSEN-1 and PSEN-2). (Alzheimer’s Society, 2007).
On the other hand, the late onset disease occurs more frequently than the early onset disease. The gene that is responsible for the development of this condition is the apolipoprotein E (APOE) gene located on the 19th chromosome (Alzheimer’s Society, 2007). This gene is denoted by the Greek letter epsilon (ε) and has three forms namely: APOE ε2, ε3, and ε4. Each individual has six copies of the gene that occurs in three combinations. Elevated risks of developing AD are linked to the APOE ε4 gene. In contrast, the APOE ε3 gene poses an average probability of developing the condition and the APOE ε2 gene poses the least risk of all in developing the condition.
Scientists use several genomic techniques to...