N. Durany et al., No association between alpha(1)-antichymotrypsin and apolipoprotein E in Alzheimer's disease and vascular dementia, ALZHEIM REP, 2(3), 1999, pp. 159-164
Genetic studies have identified the apolipoprotein epsilon 4 allele (apoE e
psilon 4) as a major risk factor for Alzheimer's disease (AD) and possibly
vascular dementia (VD), however, apoE epsilon 4 is neither necessary nor su
fficient to cause dementia. It has therefore been postulated that other gen
etic or non-genetic factors must be involved in the manifestation of the di
sease. The protein al-antichymotrypsin (ACT) is a good candidate for one su
ch factor, as it is associated with amyloid deposits in Alzheimer's disease
, promotes the polymerization of Ap peptide into amyloid filaments in vivo,
and increases the neurotoxicity of AP peptide. In our study of a German po
pulation we have analyzed the apoE and ACT genotypes in AD and VD patients
and controls in an attempt to show whether the allele ACT-A is associated w
ith apoE epsilon 4 not only in AD but also in VD. Our results show a clear
association between apoE epsilon 4 and AD but not with VD and no associatio
n between the ACT genotype and dementia, nor between the presence of both t
he ACT-A allele and apoE epsilon 4 allele and AD. Assuming that the apoE ep
silon 4 allele is a risk factor for AD these findings suggest that the effe
ct of the ACT signal peptide polymorphism on AD, if present, is at most ver
y small.