The A allele of a common A-T polymorphism in the signal peptide of alpha(1)-antichymotrypsin gene (ACT) has been reported to contribute a two- to threefold increased risk to Alzheimer's disease (AD) patients who carry the apolipoprotein E epsilon4 (APOE epsilon4) genotype. Since the ACT expression in AD brains is enhanced in particular in areas that develop amyloid plaques, the ACT polymorphism is considered to be a good candidate gene. We have analyzed this polymorphism in 102 AD patients and 191 matched controls, all originating from Western Germany. No statistically significant differences in allele frequencies and in genotype distribution of ACT could be shown between AD patients and controls. When we analyzed the polymorphism in APOE epsilon4 carriers, no overrepresentation in our AD group could be shown for the ACT*AA genotype carriers. Copyrightz1999S.KargerAG,Basel