Background: In a previous genome survey, we detected associations of allele
s at six microsatellite loci with typical-onset AD, including the 234bp all
ele of the D10S1423 locus. The goal of the current study was to explore the
clinical, neuropathalogical, and neurochemical correlates of the D10S1423
234bp allele in a group of 50 autopsy-confirmed cases of Alzheimer's diseas
e (AD) who lacked other brain diseases.
Methods: Clinical assessments were performed as part of a longitudinal stud
y of AD and related disorders. Autopsies were performed using standardized
methods and diagnoses were made according to established criteria. Genotypi
ng, morphometry, and neurochemical analyses were performed using postmortem
brain tissue.
Results: Patients with AD who carried the D10S1423 234bp allele manifested
substantial reductions in dopamine levels in all six cortical regions exami
ned. In contrast carriers tended to have higher concentrations of cortical
norepinephrine and revealed a dosage effect of the D10S1423 234bp allele.
Conclusions: These findings support the results of our genome survey and su
ggest that a novel susceptibility gene far AD resides near the D10S1423 loc
us. The characterization of biologically meaningful subtypes, including gen
otypic subtypes with particular neurobiological derangements, may be import
ant for the advancement of experimental therapeutics in AD. (C) 1999 Societ
y of Biological Psychiatry.