Cathepsin D (catD) is an intracellular acid protease possibly involved in A
lzheimer's disease (AD)-related neurodegeneration through cleavage of amylo
id precursor protein into amyloidogenic components. We studied whether an e
xonic polymorphism of the catD gene (C --> T [Ala --> Val] transition at po
sition 224), which possibly influences pro-catD secretion and intracellular
maturation of the enzyme, was associated with the risk for the development
of AD in 127 demented patients and 184 controls. The catD*T allele was sig
nificantly overrepresented in demented patients (11.8%) compared with nonde
mented controls (4.9%). Carriers of the catD*T allele had a 3.1-fold increa
sed risk for developing AD than noncarriers. Carriers of the apolipoprotein
E (ApoE) epsilon 4 allele (ApoE*4) had a 3.9-fold increased risk than non-
carriers. The adjusted odds ratio for subjects with the ApoE*4 and the catD
*T allele was 19.0 compared with subjects with neither of these two alleles
. Our data confirm the results of a recently performed pilot study in an in
dependent sample and suggest that the catD genotype is strongly associated
with the risk for AD.