re of this type. FAD is suspected when Alzheimers disease can be traced over several generations and there is a history of (among previously affected family members) a similar age of onset and duration of the disease (usually 4 years). Approximately 50% of the children of an affected parent go on to develop the disease (Pollen, 1993, p.89). Much research has been conducted in an attempt to locate the gene that is responsible for FAD. Currently, researchers have isolated genes 1, 14, and 21 (Alzheimer's, 1996, p.36). However, the evidence still remains inconclusive (Statement, 1996, p.2). There is also a possibility that a specific genetic mutation merely puts a person at risk to the disease and Alzheimers disease is triggered by an external force, like a head injury (Statement, 1996, p.4). Finding the specific location of the gene will pave the way for a diagnostic or even predictive test for FAD. Similar genetic tests already exist for cystic fibrosis and muscular dystrophy. Locating the Alzheimers disease gene will also allow scientists to study why the particular gene is not functioning properly and may give clues for treatment and possible cures. The long term goal of this research is the same as that of any other genetic research and that is gene therapy - which is the possibility that science could one day alter our genetic make-up. The other much more common type of the disease is Sporadic Alzheimer's Disease (SAD). This includes all other types of the disease which are not linked to heredity. Genetic research is also playing a major role in the progress towards a diagnostic or predictive test for SAD. Recently, a gene involved in the transport of cholesterol has been identified to be associated with Alzheimers disease. Apolipoprotein E is located on chromosome 19 and seems to contribute to the susceptibility of a person with Alzheimers disease (Statement, 1996, p.6). The gene exists in three different forms...
