Advances in genetic testing for Alzheimer's disease.

As the prevalence of Alzheimer's disease (AD), the most common dementia in the elderly, continues to increase, neurologists will encounter a growing number of questions about genetic testing for dementia patients, their relatives, and people concerned about memory or cognitive function who have no apparent risk except advancing age. Until recently, clinical gene testing only included apolipoprotein E genotyping and testing for presenilin 1 mutations. In 2008, testing expanded to include the presenilin 2 and amyloid precursor protein genes. Despite these advances, genetic testing is currently not appropriate for most individuals diagnosed with AD and has limited utility for predictive purposes. Further research, however, is likely to expand the usefulness of this testing for both dementia patients and their relatives. If genetic testing is undertaken, thorough counseling, whether by the physician or a qualified genetic counselor, is an integral component of the testing process for both affected individuals and their families.