Genetics of Alzheimer's disease.

We briefly reviewed methods of psychiatric genetics and showed how these have elucidated genetic aspects of Alzheimer's disease. Although some cases of Alzheimer's disease are not familial, clinicians and researchers have identified many families in which the disease occurs in multiple generations in approximately 50% of family members. Linkage analyses have implicated several genes as causes or risk factors for Alzheimer's disease in different families: the amyloid precursor protein gene, the apolipoprotein-E gene (E4 subtype) on chromosome 19, the S182 gene on chromosome 14 and the STM2 gene on chromosome 1. These linkage findings have been replicated in independent laboratories and, thus, provide strong evidence for genetic heterogeneity of this disease. The discovery of these genes may lead to a better understanding of the etiology and pathophysiology of Alzheimer's disease and also raises the possibility of genetic counseling for patients with familial Alzheimer's disease.