Apolipoprotein E genotyping in Alzheimer's disease

Apolipoprotein E(APOE=gene; apoE=protein) is the first identified genetic susceptibility factor for sporadic Alzheimer's disease (AD). The application of APOE genotyping to the prediction and diagnosis of AD has been a source of controversy for the public and for clinicians and scientists. These issues were explored by a 33 member working group in a two-day conference held in October, 1995, and sponsored by the National Institute on Aging, the Alzheimer's Association (USA), and other organisations. The group's conclusions are: The use of APOE genotyping to predict future risk of AD in symptom-free individuals is not recommended at this time. Insofar as patients with AD are more likely to have an APOE-epsilon 4 allele than are patients with other forms of dementia or individuals without dementia, physicians may choose to use APOE genotyping as an adjunct to other diagnostic tests for AD. Since genotyping cannot provide certainty about the presence or absence of AD, it should not be used as the sole diagnostic test. In deciding whether or not to carry out APOE genotyping for any purpose, physicians and patients should bear in mind that genotype disclosure can have adverse effects on insurability, employability, and the psychosocial status of patients and family members. Clinical and research applications of APOE genotyping must:be linked to adequate pre-test and post-test counselling, education, and psychosocial support. Research priorities include large-scale, prospective investigations of dementia incidence as a function of APOE genotype, and the development of novel approaches to the prevention and treatment of AD based on knowledge of the role in the disorder played by APOE and other factors.