title: Genetic aspects of Alzheimer disease.
abstract: BACKGROUND
  Alzheimer disease (AD) is a genetically complex disorder. Mutations in 3 genes, presenilin 1, amyloid precursor protein, and presenilin 2, lead to early-onset familial AD in rare families with onset of disease occurring prior to age 65. Specific polymorphisms in apolipoprotein E are associated with the more common, late-onset AD occurring after age 65. In this review, we discuss current advances in AD genetics, the implications of the known AD genes, presenilin 1, presenilin 2, amyloid precursor protein, and apolipoprotein E, and other possible genes on the clinical diagnosis, treatment, and genetic counseling of patients and families with early- and late-onset AD.
  
  
  RESULTS
  In addition to the mutations in 4 known genes associated with AD, mutations in other genes may be implicated in the pathogenesis of the disease. Most recently, 2 different research groups have reported genetic association between 2 genes, sortilin-related receptor and GAB2, and AD. These associations have not changed the diagnostic and medical management of AD.
  
  
  CONCLUSIONS
  New research in the genetics of AD have implicated novel genes as having a role in the disease, but these findings have not been replicated nor have specific disease causing mutations been identified. To date, clinical genetic testing is limited to familial early-onset disease for symptomatic individuals and asymptomatic relatives and, although not recommended, amyloid precursor protein apolipoprotein E testing as an adjunct to diagnosis of symptomatic individuals.
authors.affiliation: Taub Institute for Research on Alzheimer Disease and the Aging Brain and the Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, Department of Neurology, New York, NY 10032, USA. jlw61@columbia.edu
authors.forename: Jennifer
authors.initials: J
authors.lastname: Williamson
authors.forename: Jill
authors.initials: J
authors.lastname: Goldman
authors.forename: Karen S
authors.initials: KS
authors.lastname: Marder
mesh_terms: D000544:Alzheimer Disease / Q000209:etiology / Q000235:genetics*; D000818:Animals; D020022:Genetic Predisposition to Disease; D006801:Humans