Genetics and its use in Alzheimer's disease.

How useful is genetics to a clinician who treats patients with Alzheimer's disease (AD)? Even though much has been learned about the genetics of AD, given the current state of knowledge, the application of genetics to clinical practice is limited. Three genes (amyloid precursor protein [APP], presenilin 1, and presenilin 2) are primarily responsible for only part of early-onset AD, and the apolipoprotein E (APOE) gene elevates risk but does not confer risk deterministically. In addition, several candidate chromosomal regions are being investigated now. To accurately determine genetic profile so that it can be used in a clinical setting as a screening or diagnostic tool, much research is needed.