title: Plasma amyloid beta protein is elevated in late-onset Alzheimer disease families.
abstract: OBJECTIVE
  Plasma A beta levels are elevated in early-onset Alzheimer disease (AD) caused by autosomal dominant mutations. Our objective was to determine whether similar genetic elevations exist in late-onset AD (LOAD).
  
  
  METHODS
  We measured plasma A beta in first-degree relatives of patients with LOAD in a cross-sectional series and in extended LOAD families. We screened these subjects for pathogenic mutations in early-onset AD genes and determined their ApoE genotypes.
  
  
  RESULTS
  Plasma A beta is significantly elevated in the LOAD first-degree relatives in comparison to unrelated controls and married-in spouses. These elevations are not due to ApoE epsilon 4 or pathogenic coding mutations in the known early-onset AD genes.
  
  
  CONCLUSIONS
  The findings provide strong evidence for the existence of novel, as yet unknown genetic factors that affect late-onset Alzheimer disease by increasing A beta.
authors.affiliation: Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road South, Jacksonville, FL 32224, USA.
authors.forename: N
authors.initials: N
authors.lastname: Ertekin-Taner
authors.forename: L H
authors.initials: LH
authors.lastname: Younkin
authors.forename: D M
authors.initials: DM
authors.lastname: Yager
authors.forename: F
authors.initials: F
authors.lastname: Parfitt
authors.forename: M C
authors.initials: MC
authors.lastname: Baker
authors.forename: S
authors.initials: S
authors.lastname: Asthana
authors.forename: M L
authors.initials: ML
authors.lastname: Hutton
authors.forename: S G
authors.initials: SG
authors.lastname: Younkin
authors.forename: N R
authors.initials: NR
authors.lastname: Graff-Radford
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood* / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000097:blood*; D053327:Apolipoprotein E4 / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005192:Family Health; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood; D011110:Polymorphism, Genetic; D053763:Presenilins / Q000235:genetics; D011569:Psychiatric Status Rating Scales; D012737:Sex Factors; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D010446:Peptide Fragments; D053763:Presenilins; C075222:amyloid beta-protein (1-42)